electroactive-polymer-nanoparticles-exhibiting-photothermal-properties

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Texas State University

High levels of circulating glucocorticoid hormone may be important mediators for elevating resting metabolic rate upon severe injury or stress. We therefore investigated the effect of dexamethasone on mitochondrial biogenesis in rats (6 mg/kg daily) as well as in cells in culture (1 microM) over a period of 3 d. A marked stimulation of mitochondrial DNA transcription and increased levels of cytochrome c oxidase activity were found in skeletal muscle of rats and differentiated mouse C2C12 muscle cells, but not in other tissues, myoblasts, or other cell lines. The effect was inhibited by RU486. Therefore, increased occupancy of glucocorticoid receptors is necessary, but not sufficient to increase mitochondrial biogenesis and other, skeletal muscle specific factors are postulated. Expression of the mitochondrial transcription factor A was unchanged, suggesting a possible involvement of the recently described mitochondrial glucocorticoid receptor. Expression of uncoupling protein-3 was also unchanged. In conclusion, our results show that high levels of glucocorticoid hormone are sufficient to stimulate mitochondrial biogenesis; however, only in skeletal muscle. Increased mitochondrial mass in this tissue, without changes of the coupling state of the respiratory chain, might be the molecular basis for the elevated resting metabolic rate observed under high cortisol levels in humans.

Glucocorticoid hormone stimulates mitochondrial biogenesis specifically in skeletal muscle.

In order to test the hypothesis that an imbalance between energy requirement and energy supply regulates mitochondrial genes and ultimately mitochondrial biogenesis, energy supply was challenged in HepG2 cells by withdrawal of glucose from the culture medium, making the cells exclusively dependent on mitochondrial ATP production. Such cells showed a 2-fold increase of cytochrome c oxidase activity, elevated levels of mitochondrial DNA, mitochondrial DNA encoded mRNAs and proteins, as well as the nuclear encoded mitochondrial transcription factor A. Lactate production was significantly reduced and glutamine was consumed as an alternative substrate for oxidative metabolism. Long-term adapted cells formed exclusively monolayers, while they normally grow in multilayers forming tumor spheroids. Also, long-term adapted cells proliferated significantly faster. No differences for the ATP/ADP ratio were observed, indicating that this is not the primary signal initiating the adaptative processes. These results show that mitochondrial biogenesis and oxidative metabolism are stimulated in HepG2 cells grown in the absence of fermentable glucose, probably in order to compensate for the diminished supply of glycolytic ATP.

Cultivation in glucose-deprived medium stimulates mitochondrial biogenesis and oxidative metabolism in HepG2 hepatoma cells.

In contrast to the recently reported cyclodimerisations of phosphaalkynes, alkynes preferably trimerise at the same low-valent iron(-I) centre.

P-C dichotomy: divergent iron(-I)-mediated alkyne and phosphaalkyne cycloligomerisations.

&#x6C22;&#x9176;&#x86CB;&#x767D;&#x50AC;&#x5316;&#x6C22;&#x5206;&#x5B50;&#x53EF;&#x9006;&#x8F6C;&#x6362;&#x4E3A;&#x8D28;&#x5B50;&#x548C;&#x7535;&#x5B50;&#x3002;[NiFe] &#x6C22;&#x9176;&#x7684;&#x8BB8;&#x591A;&#x9176;&#x56FD;&#x5BB6;&#x5DF2;&#x88AB;&#x5E7F;&#x6CDB;&#x7814;&#x7A76;&#xFF0C;&#x4F46;&#x6709;&#x591A;&#x4E2A;&#x50AC;&#x5316;&#x6709;&#x5173; EPR &#x6C89;&#x9ED8;&#x72B6;&#x6001;&#x4ECD;&#x7136;&#x5F88;&#x5DEE;&#x7684;&#x7279;&#x70B9;&#x3002;&#x4F7F;&#x7528;&#x65B0;&#x7684;&#x5149;&#x8C31;&#x6280;&#x672F;&#x7684;&#x6A21;&#x578B;&#x5316;&#x5408;&#x7269;&#x7684;&#x5206;&#x6790;&#x53EF;&#x4EE5;&#x4E3A;&#x8FD9;&#x4E9B;&#x96BE;&#x4EE5;&#x6349;&#x6478;&#x7684;&#x56FD;&#x5BB6;&#x5185;&#x86CB;&#x767D;&#x8D28;&#x7684;&#x7814;&#x7A76;&#x63D0;&#x4F9B;&#x4E00;&#x4E2A;&#x6846;&#x67B6;&#x3002;&#x6211;&#x4EEC;&#x5F97;&#x5230;&#x7684;&#x5149;&#x5438;&#x6536;&#x548C;&#x5171;&#x632F;&#x62C9;&#x66FC; (RR) &#x5149;&#x8C31; (dppe)Ni(&mu;-pdt)Fe(CO)(3) [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)]&#xFF0C;[NiFe] &#x8131;&#x6C22;&#x9176;&#x6D3B;&#x6027;&#x90E8;&#x4F4D;&#x7684; EPR &#x6C89;&#x9ED8;&#x954D;&#x7845;&#x548C;&#x954D;-R &#x72B6;&#x6001;&#x7684;&#x7ED3;&#x6784;&#x548C;&#x529F;&#x80FD;&#x6A21;&#x578B;&#x5316;&#x5408;&#x7269;&#x3002;&#x8FD9;&#x91CC;&#x63D0;&#x51FA;&#x7684;&#x7814;&#x7A76;&#x4F7F;&#x7528; RR &#x5149;&#x8C31;&#x63A2;&#x9488;&#x7684;&#x6D3B;&#x52A8;&#x7AD9;&#x70B9;&#xFF0C;&#x5305;&#x62EC;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x548C;&#x540C;&#x4F4D;&#x7D20;&#x66FF;&#x4EE3;&#x7528;&#x4E8E;&#x6807;&#x8BC6;&#x5173;&#x952E;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x6A21;&#x5F0F;&#x4E0E;&#x6865;&#x914D;&#x4F53;&#x91D1;&#x5C5E;&#x548C;&#x94C1;&#x94B4;&#x5F2F;&#x66F2;&#x632F;&#x52A8;&#xFF0C;&#x62C9;&#x4F38;&#x632F;&#x52A8;&#x7684;&#x632F;&#x52A8;&#x6A21;&#x5F0F;&#x3002;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x7684;&#x9707;&#x52A8;&#x662F;&#x57FA;&#x672C;&#x4E0A;&#x89E3;&#x8026;&#x548C;&#x4EE3;&#x8868;&#x5B64;&#x7ACB;&#x7684;&#x3001; &#x672C;&#x5730;&#x5316;&#x7684;&#x62C9;&#x4F38;&#x6A21;&#x5F0F; &#xFF1B;&#x94C1;-&#x6C22;&#x5316;&#x7269;&#x53D1;&#x751F;&#x632F;&#x52A8;&#x65F6;&#x53D1;&#x751F;&#x5728; 1530 cm(-1) &#x954D;&#x6C22;&#x632F;&#x52A8;&#x5728; 945 cm(-1) &#x89C2;&#x5BDF;&#x5230;&#x3002;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x7684;&#x632F;&#x52A8;&#x9891;&#x7387;&#x4E4B;&#x95F4;&#x7684;&#x91CD;&#x5927;&#x5DEE;&#x5F02;&#x53CD;&#x6620;&#x5728;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x503A;&#x5238;&#x957F;&#x5EA6;&#x7565;&#x6709;&#x4E0D;&#x5BF9;&#x79F0;&#x3002;&#x6B64;&#x5916;&#xFF0C;&#x4F9D;&#x8D56;&#x4E8E;&#x65F6;&#x95F4;&#x5BC6;&#x5EA6;&#x6CDB;&#x51FD;&#x7406;&#x8BBA; (TD-DFT) &#x8BA1;&#x7B97;&#x8FDB;&#x884C;&#x4EE5;&#x83B7;&#x5F97;&#x8FD9;&#x4E9B;&#x5316;&#x5408;&#x7269;&#x7684;&#x7406;&#x8BBA; RR &#x8C31;&#x3002;&#x6839;&#x636E;&#x7406;&#x8BBA;&#x548C;&#x5B9E;&#x9A8C;&#x7684;&#x8BE6;&#x7EC6;&#x6BD4;&#x8F83;&#xFF0C;&#x5206;&#x914D;&#x7684;&#x5360;&#x4E3B;&#x5BFC;&#x5730;&#x4F4D;&#x7684;&#x7535;&#x5B50;&#x8DC3;&#x8FC1;&#x548C; RR &#x5B9E;&#x9A8C;&#x4E2D;&#x63A2;&#x6D4B;&#x7684;&#x91CD;&#x8981;&#x6B63;&#x5E38;&#x6A21;&#x5F0F; &#xFF1B;&#x4E3B;&#x8981;&#x5728;&#x53EF;&#x89C1;&#x5149;&#x6CE2;&#x957F;&#x8F6C;&#x6362;&#x4EE3;&#x8868;&#x91D1;&#x5C5E;&#x5BF9;&#x91D1;&#x5C5E;&#x548C;&#x91D1;&#x5C5E;-&#x914D;&#x4F4D;&#x4F53;&#x7535;&#x8377;&#x8F6C;&#x79FB;&#x4E50;&#x961F;&#x3002;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x632F;&#x52A8;&#x6A21;&#x5F0F;&#x7684;&#x5171;&#x632F;&#x62C9;&#x66FC;&#x5149;&#x8C31;&#x548C;&#x79BB;&#x6563;&#x5085;&#x7ACB;&#x53F6;&#x53D8;&#x6362;&#x7684;&#x8BA1;&#x7B97;&#x4E0E;&#x89C2;&#x6D4B;&#x4E2D;&#x542B;&#x6709;&#x91D1;&#x5C5E;&#x6C22;&#x5316;&#x7269;&#x7684;&#x86CB;&#x767D;&#x7684;&#x8FD9;&#x79CD;&#x632F;&#x52A8;&#x6A21;&#x5F0F;&#x524D;&#x666F;&#x5E76;&#x8BA8;&#x8BBA;&#x7684;&#x56FA;&#x6709;&#x5C5E;&#x6027;&#x3002;&#x8FD9;&#x79CD;&#x7ED3;&#x5408;&#x7684;&#x7406;&#x8BBA;&#x4E0E;&#x5B9E;&#x9A8C;&#x65B9;&#x6CD5;&#x53EF;&#x80FD;&#x6709;&#x4EF7;&#x503C;&#x4E3A;&#x8868;&#x5F81;&#x7684;&#x7C7B;&#x4F3C;&#x6C27;&#x5316;&#x8FD8;&#x539F; [NiFe] hydrogenases &#x4E2D;&#x7684;&#x56FD;&#x5BB6;&#x3002;

[NiFe] &#x8131;&#x6C22;&#x9176;&#x6A21;&#x578B;&#x5316;&#x5408;&#x7269;&#x7531;&#x5171;&#x632F;&#x62C9;&#x66FC;&#x5149;&#x8C31;&#x548C;&#x5BC6;&#x5EA6;&#x6CDB;&#x51FD;&#x8BA1;&#x7B97;&#x7814;&#x7A76;&#x4E2D;&#x7684;&#x5173;&#x952E;&#x6C22;&#x5316;&#x7269;&#x53D1;&#x751F;&#x632F;&#x52A8;&#x6A21;&#x5F0F;&#x3002;

Hydrogenase proteins catalyze the reversible conversion of molecular hydrogen to protons and electrons. While many enzymatic states of the [NiFe] hydrogenase have been studied extensively, there are multiple catalytically relevant EPR-silent states that remain poorly characterized. Analysis of model compounds using new spectroscopic techniques can provide a framework for the study of these elusive states within the protein. We obtained optical absorption and resonance Raman (RR) spectra of (dppe)Ni(Î¼-pdt)Fe(CO)(3) and [(dppe)Ni(Î¼-pdt)(Î¼-H)Fe(CO)(3)][BF(4)], which are structural and functional model compounds for the EPR-silent Ni-SI and Ni-R states of the [NiFe] hydrogenase active site. The studies presented here use RR spectroscopy to probe vibrational modes of the active site, including metal-hydride stretching vibrations along with bridging ligand-metal and Fe-CO bending vibrations, with isotopic substitution used to identify key metal-hydride modes. The metal-hydride vibrations are essentially uncoupled and represent isolated, localized stretching modes; the iron-hydride vibration occurs at 1530 cm(-1), while the nickel-hydride vibration is observed at 945 cm(-1). The significant discrepancy between the metal-hydride vibrational frequencies reflects the slight asymmetry in the metal-hydride bond lengths. Additionally, time-dependent density functional theory (TD-DFT) calculations were carried out to obtain theoretical RR spectra of these compounds. On the basis of the detailed comparison of theory and experiment, the dominant electronic transitions and significant normal modes probed in the RR experiments were assigned; the primary transitions in the visible wavelengths represent metal-to-metal and metal-to-ligand charge transfer bands. Inherent properties of metal-hydride vibrational modes in resonance Raman spectra and DFT calculations are discussed together with the prospects of observing such vibrational modes in metal-hydride-containing proteins. Such a combined theoretical and experimental approach may be valuable for characterization of analogous redox states in the [NiFe] hydrogenases.

Key Hydride Vibrational Modes in [NiFe] Hydrogenase Model Compounds Studied by Resonance Raman Spectroscopy and Density Functional Calculations.

Prot&eacute;ines hydrog&eacute;nase catalysent la conversion r&eacute;versible de l&#39;hydrog&egrave;ne mol&eacute;culaire en protons et &eacute;lectrons. Alors que de nombreux &Eacute;tats enzymatiques de l&#39;hydrog&eacute;nase [NiFe] ont &eacute;t&eacute; &eacute;tudi&eacute;s intensivement, il y a plusieurs catalytiquement EPR-silent &Eacute;tats concern&eacute;s qui restent mal caract&eacute;ris&eacute;s. L&#39;analyse des compos&eacute;s mod&egrave;les utilisant de nouvelles techniques spectroscopiques peut fournir un cadre pour l&#39;&eacute;tude de ces &Eacute;tats insaisissables au sein de la prot&eacute;ine. Nous avons obtenu par r&eacute;sonance et l&#39;absorption optique spectres Raman (RR) de (dppe)Ni(&mu;-pdt)Fe(CO)(3) et [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)], qui sont des compos&eacute;s de mod&egrave;les structuraux et fonctionnels pour les EPR en silence Ni-SI et Ni-R du site actif de l&#39;hydrog&eacute;nase [NiFe]. Les &eacute;tudes pr&eacute;sent&eacute;es ici utilisent la spectroscopie RR pour sonder les modes vibrationnels du site actif, y compris les vibrations d&#39;&eacute;longation m&eacute;tal-hydrure avec pontage ligand-m&eacute;tal et vibrations de flexion Fe-CO, avec substitution isotopique permet d&#39;identifier les principaux modes de m&eacute;tal-hydrure. Les vibrations du m&eacute;tal-hydrure sont essentiellement d&eacute;coupl&eacute;es et repr&eacute;sentent les modes d&#39;&eacute;tirements isol&eacute;s, localis&eacute;es ; le fer-hydrure vibre &agrave; 1530 cm(-1), tandis que la vibration de nickel-hydrure est observ&eacute;e &agrave; 945 cm(-1). L&#39;&eacute;cart important entre les fr&eacute;quences de vibration de m&eacute;tal-hydrure refl&egrave;te la l&eacute;g&egrave;re asym&eacute;trie dans les longueurs des liaisons m&eacute;tal-hydrure. En outre, des calculs de th&eacute;orie de la fonctionnelle (TD-DFT) densit&eacute; d&eacute;pendante du temps ont &eacute;t&eacute; r&eacute;alis&eacute;es afin d&#39;obtenir des spectres RR th&eacute;oriques de ces compos&eacute;s. Sur la base de la comparaison d&eacute;taill&eacute;e de la th&eacute;orie et l&#39;exp&eacute;rience, les transitions &eacute;lectroniques dominantes et importants modes normaux sond&eacute;s dans les exp&eacute;riences de RR ont &eacute;t&eacute; assign&eacute;s ; les transitions primaires dans les longueurs d&#39;onde visibles repr&eacute;sentent des bandes de transfert de charge de m&eacute;tal-m&eacute;tal et m&eacute;tal-ligand. Propri&eacute;t&eacute;s inh&eacute;rentes des modes vibrationnels de m&eacute;tal-hydrure en r&eacute;sonance les spectres Raman et calculs DFT sont discut&eacute;s ainsi que les perspectives d&#39;observer ces modes de vibration dans les prot&eacute;ines contenant du m&eacute;tal-hydrure. Telle une approche th&eacute;orique et exp&eacute;rimentale combin&eacute;e peut &ecirc;tre utile pour la caract&eacute;risation des &Eacute;tats redox analogue dans les hydrog&eacute;nases [NiFe].

Hydrure principaux Modes vibrationnels dans [NiFe] hydrog&eacute;nase mod&egrave;le compos&eacute;s &eacute;tudi&eacute;s par spectroscopie de Raman de r&eacute;sonance et de la densit&eacute; des calculs fonctionnels.

Hydrogenase Proteine katalysieren die reversible Umwandlung von molekularem Wasserstoff in Protonen und Elektronen. W&auml;hrend viele enzymatische Staaten von der [NiFe] Hydrogenase ausgiebig studiert haben, gibt es mehrere katalytisch relevanten EPR stumm Zust&auml;nde, die bleiben schlecht charakterisiert. Analyse der Modell-Verbindungen mit neue spektroskopische Methoden kann ein Rahmenwerk f&uuml;r das Studium dieser schwer fassbare Zust&auml;nde innerhalb des Proteins. Wir erhalten optische Absorption und Resonanz Raman (RR) Spektren (dppe)Ni(&mu;-pdt)Fe(CO)(3) und [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)], die strukturellen und funktionellen Modell Compounds f&uuml;r den EPR stumm Ni-SI- und Ni-R Staaten des Standortes [NiFe] Hydrogenase aktiv sind. Die hier vorgestellten Studien verwenden RR-Spektroskopie, um Schwingungs Modi der aktiv-Seite, inklusive Metall-Hydrid Aufspannung Schwingungen zusammen mit bridging Ligand-Metall und Fe-CO-Biege-Vibrationen, mit Isotopen Substitution zum Schl&uuml;ssel-Metall-Hydrid-Modi zu identifizieren. Die Metall-Hydrid-Schwingungen sind im wesentlichen abgekoppelt und isoliert, lokalisierte Aufspannung Modi; die Eisen-Hydrid-Vibrationen erfolgt auf 1530 cm(-1), w&auml;hrend die Nickel-Hydrid-Vibration bei 945 cm(-1) beobachtet wird. Die deutliche Diskrepanz zwischen den Metall-Hydrid-Schwingungs-Frequenzen reflektiert die leichte Asymmetrie in der Metall-Hydrid-Bindungsl&auml;ngen. Dar&uuml;ber hinaus zeitabh&auml;ngige Dichte funktionalen Theorie (TD-DFT) Berechnungen erfolgten theoretische RR-Spektren dieser Verbindungen zu erhalten. Auf der Grundlage der detaillierten Vergleich von Theorie und Experiment waren die dominierende elektronische &Uuml;berg&auml;nge und bedeutende normale Modi sondiert in den RR-Experimenten zugeordnet; die prim&auml;re &Uuml;berg&auml;nge in den sichtbaren Wellenl&auml;ngen darstellen Metall-Metall und Metall-Ligand-Charge-Transfer-B&auml;nder. Inh&auml;renten Eigenschaften der Schwingungs-Metallhydrid Modi in Resonanz, die Raman-Spektren und DFT-Berechnungen sowie die Aussichten f&uuml;r die Erfassung solcher Schwingungs-Modi in Metall-Hydrid-haltige Proteine diskutiert werden. Solch ein kombinierter theoretischer und experimenteller Ansatz m&ouml;glicherweise wertvoll f&uuml;r die Charakterisierung von Analog Redox-Staaten in [NiFe]-Hydrogenases.

Schl&uuml;ssel-Hydrid Schwingungs-Modi in [NiFe] Hydrogenase Modell Verbindungen von Resonanz-Raman-Spektroskopie und Dichte funktionell Berechnungen untersucht.

Le proteine idrogenasi catalizzano la conversione reversibile di idrogeno molecolare in protoni ed elettroni. Mentre molti stati enzimatici dell&#39;idrogenasi [NiFe] sono stati studiati estesamente, ci sono multiple cataliticamente EPR-silent Stati interessati che rimangono scarsamente caratterizzati. Analisi di composti modello utilizzando nuove tecniche spettroscopiche possono fornire un quadro per lo studio di questi stati sfuggenti all&#39;interno della proteina. Abbiamo ottenuto risonanza e assorbimento ottico spettri Raman (RR) (dppe)Ni(&mu;-pdt)Fe(CO)(3) e [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)], che sono composti di modello strutturale e funzionale per gli Stati EPR-silent Ni-SI e Ni-R del sito attivo [NiFe] idrogenasi. Gli studi presentati qui utilizzano spettroscopia RR per sonda modi vibrazionali del sito attivo, compresi stretching vibrazioni-idruro di metallo con bridging ligando-metallo e vibrazioni flettenti Fe-CO, con sostituzione isotopica utilizzato per identificare la chiave-metallo-idruro modalit&agrave;. Le vibrazioni-idruro di metallo sono essenzialmente disgiunti e rappresentano modalit&agrave; di stretching isolata, localizzata; la vibrazione di ferro-idrato si verifica al 1530 cm(-1), mentre la vibrazione all&#39;idruro di nichel &egrave; osservata a 945 cm(-1). La significativa discrepanza tra le frequenze vibrazionali-idruro di metallo riflette la leggera asimmetria nelle lunghezze di legame metallo-idruro. Inoltre, i calcoli (TD-DFT) teoria del funzionale densit&agrave; dipendente dal tempo sono stati effettuati per ottenere spettri RR teorici di questi composti. Sulla base del confronto dettagliato tra teoria ed esperimento, furono assegnate le transizioni elettroniche dominante e significativi modi normali sono state esaminate negli esperimenti RR; le transizioni primarie le lunghezze d&#39;onda visibili rappresentano bande di trasferimento di carica di metallo e metallo-ligando. Propriet&agrave; intrinseche dei modi vibrazionali-idruro di metallo in risonanza gli spettri Raman e calcoli DFT sono discussi insieme le prospettive di osservare tali modi vibrazionali in proteine contenenti metallo-idruro. Un approccio teorico e sperimentale combinato possa essere prezioso per la caratterizzazione degli Stati analoga redox nella hydrogenases [NiFe].

Chiave idruro modi vibrazionali in [NiFe] idrogenasi modello mescole studiate dalla spettroscopia Raman di risonanza e densit&agrave; funzionali calcoli.

&#x30D2;&#x30C9;&#x30ED;&#x30B2;&#x30CA;&#x30FC;&#x30BC;&#x86CB;&#x767D;&#x8CEA;&#x5206;&#x5B50;&#x306E;&#x6C34;&#x7D20;&#x306E;&#x53EF;&#x9006;&#x7684;&#x8EE2;&#x63DB;&#x967D;&#x5B50;&#x3068;&#x96FB;&#x5B50;&#x306B;&#x89E6;&#x5A92;&#x4F5C;&#x7528;&#x3092;&#x53CA;&#x307C;&#x3057;&#x307E;&#x3059;&#x3002;[NiFe] &#x30D2;&#x30C9;&#x30ED;&#x30B2;&#x30CA;&#x30FC;&#x30BC;&#x306E;&#x9175;&#x7D20;&#x7684;&#x8AF8;&#x5DDE;&#x304C;&#x5E83;&#x304F;&#x7814;&#x7A76;&#x3055;&#x308C;&#x3066;&#x3044;&#x308B;&#x304C;&#x3001;&#x4E0D;&#x5B8C;&#x5168;&#x7279;&#x5FB4;&#x4ED8;&#x3051;&#x3089;&#x308C;&#x308B;&#x307E;&#x307E;&#x8907;&#x6570;&#x89E6;&#x5A92;&#x95A2;&#x9023;&#x306E; EPR &#x30B5;&#x30A4;&#x30EC;&#x30F3;&#x30C8;&#x72B6;&#x614B;&#x3067;&#x3059;&#x3002;&#x65B0;&#x3057;&#x3044;&#x5206;&#x5149;&#x6CD5;&#x3092;&#x7528;&#x3044;&#x305F;&#x30E2;&#x30C7;&#x30EB;&#x5316;&#x5408;&#x7269;&#x306E;&#x5206;&#x6790;&#x30D5;&#x30EC;&#x30FC;&#x30E0;&#x30EF;&#x30FC;&#x30AF;&#x3053;&#x308C;&#x3089;&#x3068;&#x3089;&#x3048;&#x3069;&#x3053;&#x308D;&#x306E;&#x306A;&#x3044;&#x72B6;&#x614B;&#x5185;&#x86CB;&#x767D;&#x8CEA;&#x306E;&#x7814;&#x7A76;&#x3092;&#x63D0;&#x4F9B;&#x3067;&#x304D;&#x307E;&#x3059;&#x3002;&#x6211;&#x3005; &#x304C;&#x5F97;&#x5149;&#x5438;&#x53CE;&#x3068;&#x5171;&#x9CF4;&#x30E9;&#x30DE;&#x30F3; (RR) &#x306E;&#x30B9;&#x30DA;&#x30AF;&#x30C8;&#x30EB; (dppe)Ni(&mu;-pdt)Fe(CO)(3) [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)]&#x3001;EPR &#x30B5;&#x30A4;&#x30EC;&#x30F3;&#x30C8; Ni SI &#x304A;&#x3088;&#x3073; Ni R &#x72B6;&#x614B; [NiFe] &#x30D2;&#x30C9;&#x30ED;&#x30B2;&#x30CA;&#x30FC;&#x30BC;&#x6D3B;&#x6027;&#x90E8;&#x4F4D;&#x306E;&#x69CB;&#x9020;&#x3068;&#x6A5F;&#x80FD;&#x306E;&#x30E2;&#x30C7;&#x30EB;&#x5316;&#x5408;&#x7269;&#x3067;&#x3042;&#x308A;&#x307E;&#x3059;&#x3002;&#x3053;&#x3053;&#x306B;&#x63D0;&#x793A;&#x7814;&#x7A76; RR &#x5206;&#x5149;&#x632F;&#x52D5;&#x30E2;&#x30FC;&#x30C9; &#x30EA;&#x30AC;&#x30F3;&#x30C9;&#x91D1;&#x5C5E;&#x3068; FE-CO &#x7CFB;&#x306E;&#x66F2;&#x3052;&#x632F;&#x52D5;&#x540C;&#x4F4D;&#x4F53;&#x7F6E;&#x63DB;&#x3068;&#x4E3B;&#x8981;&#x91D1;&#x5C5E;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x306E;&#x30E2;&#x30FC;&#x30C9;&#x3092;&#x8B58;&#x5225;&#x3059;&#x308B;&#x305F;&#x3081;&#x306E;&#x30D6;&#x30EA;&#x30C3;&#x30B8;&#x3068;&#x3068;&#x3082;&#x306B;&#x91D1;&#x5C5E;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x4F38;&#x7E2E;&#x632F;&#x52D5;&#x3092;&#x542B;&#x3080;&#x3001;&#x30A2;&#x30AF;&#x30C6;&#x30A3;&#x30D6; &#x30B5;&#x30A4;&#x30C8;&#x306E;&#x30D7;&#x30ED;&#x30FC;&#x30D6;&#x3092;&#x4F7F;&#x7528;&#x3057;&#x3066;&#x304F;&#x3060;&#x3055;&#x3044;&#x3002;&#x91D1;&#x5C5E;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x306E;&#x632F;&#x52D5;&#x304C;&#x672C;&#x8CEA;&#x7684;&#x306B;&#x7D50;&#x5408;&#x3055;&#x308C;&#x3001;&#x5B64;&#x7ACB;&#x3057;&#x3001;&#x30ED;&#x30FC;&#x30AB;&#x30E9;&#x30A4;&#x30BA;&#x3055;&#x308C;&#x305F;&#x30B9;&#x30C8;&#x30EC;&#x30C3;&#x30C1; &#x30E2;&#x30FC;&#x30C9;&#x3092;&#x8868;&#x3059;;&#x30CB;&#x30C3;&#x30B1;&#x30EB;&#x6C34;&#x7D20;&#x306E;&#x632F;&#x52D5; 945 cm(-1) &#x3067;&#x89B3;&#x6E2C;&#x3055;&#x308C;&#x308B;&#x304C;&#x9244;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x632F;&#x52D5; 1530 cm(-1) &#x3067;&#x767A;&#x751F;&#x3057;&#x307E;&#x3059;&#x3002;&#x91D1;&#x5C5E;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x306E;&#x632F;&#x52D5;&#x306E;&#x5468;&#x6CE2;&#x6570;&#x306E;&#x5927;&#x304D;&#x306A;&#x5DEE;&#x7570;&#x306F;&#x6C34;&#x7D20;&#x7D50;&#x5408;&#x9577;&#x306B;&#x304A;&#x3051;&#x308B;&#x308F;&#x305A;&#x304B;&#x306A;&#x975E;&#x5BFE;&#x79F0;&#x6027;&#x3092;&#x53CD;&#x6620;&#x3057;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002;&#x3055;&#x3089;&#x306B;&#x3001;&#x6642;&#x9593;&#x4F9D;&#x5B58;&#x5BC6;&#x5EA6;&#x6C4E;&#x95A2;&#x6570;&#x7406;&#x8AD6; (DFT TD) &#x8A08;&#x7B97;&#x7406;&#x8AD6;&#x306E; RR &#x30B9;&#x30DA;&#x30AF;&#x30C8;&#x30EB;&#x3053;&#x308C;&#x3089;&#x306E;&#x5316;&#x5408;&#x7269;&#x3092;&#x53D6;&#x5F97;&#x3059;&#x308B;&#x304C;&#x5B9F;&#x65BD;&#x3055;&#x308C;&#x307E;&#x3057;&#x305F;&#x3002;&#x7406;&#x8AD6;&#x3068;&#x5B9F;&#x9A13;&#x306E;&#x8A73;&#x7D30;&#x306A;&#x6BD4;&#x8F03;&#x306B;&#x57FA;&#x3065;&#x3044;&#x3066;&#x306F;&#x3001;&#x652F;&#x914D;&#x7684;&#x306A;&#x96FB;&#x5B50;&#x9077;&#x79FB;&#x3068; RR &#x5B9F;&#x9A13;&#x3067;&#x63A2;&#x308B;&#x91CD;&#x8981;&#x306A;&#x30CE;&#x30FC;&#x30DE;&#x30EB; &#x30E2;&#x30FC;&#x30C9;&#x306B;&#x5272;&#x308A;&#x5F53;&#x3066;&#x3089;&#x308C;&#x307E;&#x3057;&#x305F;&#x3002;&#x53EF;&#x8996;&#x6CE2;&#x9577;&#x4E00;&#x6B21;&#x9077;&#x79FB;&#x91D1;&#x5C5E;-&#x91D1;&#x5C5E;&#x3068;&#x91D1;&#x5C5E;-&#x30EA;&#x30AC;&#x30F3;&#x30C9;&#x306E;&#x96FB;&#x8377;&#x8EE2;&#x9001;&#x30D0;&#x30F3;&#x30C9;&#x3092;&#x8868;&#x3057;&#x307E;&#x3059;&#x3002;&#x91D1;&#x5C5E;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x306E;&#x632F;&#x52D5;&#x30E2;&#x30FC;&#x30C9;&#x306E;&#x5171;&#x9CF4;&#x30E9;&#x30DE;&#x30F3; &#x30B9;&#x30DA;&#x30AF;&#x30C8;&#x30EB;&#x3068; DFT &#x8A08;&#x7B97;&#x3092;&#x4E00;&#x7DD2;&#x306B;&#x3053;&#x306E;&#x3088;&#x3046;&#x306A;&#x632F;&#x52D5;&#x30E2;&#x30FC;&#x30C9;&#x91D1;&#x5C5E;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x542B;&#x6709;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x3067;&#x89B3;&#x5BDF;&#x3059;&#x308B;&#x3053;&#x3068;&#x306E;&#x898B;&#x901A;&#x3057;&#x306B;&#x3064;&#x3044;&#x3066;&#x306F;&#x8AAC;&#x660E;&#x306E;&#x56FA;&#x6709;&#x306E;&#x6027;&#x8CEA;&#x3002;&#x3053;&#x306E;&#x3088;&#x3046;&#x306A;&#x7D50;&#x5408;&#x306E;&#x7406;&#x8AD6;&#x7684;&#x30FB;&#x5B9F;&#x9A13;&#x7684;&#x30A2;&#x30D7;&#x30ED;&#x30FC;&#x30C1;&#x306F;&#x985E;&#x4F3C;&#x3057;&#x3066;&#x30EC;&#x30C9;&#x30C3;&#x30AF;&#x30B9;&#x72B6;&#x614B; [NiFe] &#x30D2;&#x30C9;&#x30ED;&#x30B2;&#x30CA;&#x30FC;&#x30BC;&#x306E;&#x8A55;&#x4FA1;&#x306E;&#x4FA1;&#x5024;&#x304C;&#x3042;&#x308A;&#x307E;&#x3059;&#x3002;

&#x30AD;&#x30FC;&#x6C34;&#x7D20;&#x5316;&#x7269;&#x5171;&#x9CF4;&#x30E9;&#x30DE;&#x30F3;&#x5206;&#x5149;&#x6CD5;&#x3068;&#x5BC6;&#x5EA6;&#x6C4E;&#x95A2;&#x6570;&#x8A08;&#x7B97;&#x306B;&#x3088;&#x308B;&#x7814;&#x7A76; [NiFe] &#x30D2;&#x30C9;&#x30ED;&#x30B2;&#x30CA;&#x30FC;&#x30BC; &#x30E2;&#x30C7;&#x30EB;&#x5316;&#x5408;&#x7269;&#x306E;&#x632F;&#x52D5;&#x30E2;&#x30FC;&#x30C9;&#x3002;

Hydrogenase &#xB2E8;&#xBC31;&#xC9C8; &#xCD09;&#xB9E4; &#xC591;&#xC131;&#xC790;&#xC640; &#xC804;&#xC790;&#xAC00; &#xC218;&#xC18C; &#xBD84;&#xC790;&#xC758; &#xAC00;&#xC5ED; &#xBCC0;&#xD658;. &#xB9CE;&#xC740; &#xD6A8;&#xC18C; &#xC0C1;&#xD0DC; [NiFe] hydrogenase&#xAC00; &#xAD11;&#xBC94;&#xC704; &#xD558; &#xAC8C; &#xACF5;&#xBD80; &#xD558;&#xB294; &#xB3D9;&#xC548; &#xAC70;&#xAE30;&#xC5D0; &#xC5EC;&#xB7EC; catalytically &#xAD00;&#xB828; EPR &#xCE68;&#xBB35; &#xC0C1;&#xD0DC;&#xB97C; &#xC720;&#xC9C0; &#xC800;&#xC870;&#xD55C; &#xAC83;&#xC774; &#xD2B9;&#xC9D5;. &#xC0C8;&#xB85C;&#xC6B4; &#xBD84; &#xAD11; &#xAE30;&#xBC95;&#xC744; &#xC0AC;&#xC6A9; &#xD558; &#xC5EC; &#xBAA8;&#xB378; &#xD654;&#xD569;&#xBB3C;&#xC758; &#xBD84;&#xC11D; &#xB2E8;&#xBC31;&#xC9C8; &#xB0B4;&#xC758; &#xC774;&#xB7EC;&#xD55C; &#xAE30;&#xBB18;&#xD55C; &#xC0C1;&#xD0DC; &#xC5F0;&#xAD6C;&#xB97C; &#xC704;&#xD55C; &#xD504;&#xB808;&#xC784; &#xC6CC;&#xD06C;&#xB97C; &#xC81C;&#xACF5;&#xD560; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;. &#xC6B0;&#xB9AC;&#xAC00; &#xC5BB;&#xC740; &#xAD11; &#xD761;&#xC218; &#xBC0F; &#xACF5;&#xBA85; &#xB77C;&#xB9CC; (RR) &#xC2A4;&#xD399;&#xD2B8;&#xB7FC; (dppe)Ni(&mu;-pdt)Fe(CO)(3) &#xBC0F; [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)], [NiFe] hydrogenase &#xD65C;&#xC131; &#xC0AC;&#xC774;&#xD2B8;&#xC758; EPR &#xC0AC;&#xC77C;&#xB7F0;&#xD2B8; Ni SI &#xBC0F; Ni R &#xC0C1;&#xD0DC;&#xC5D0; &#xB300; &#xD55C; &#xAD6C;&#xC870;&#xC640; &#xAE30;&#xB2A5; &#xBAA8;&#xB378; &#xD654;&#xD569;&#xBB3C;&#xC785;&#xB2C8;&#xB2E4;. &#xC5EC;&#xAE30;&#xC5D0; &#xC81C;&#xC2DC; &#xB41C; &#xC5F0;&#xAD6C; RR &#xBD84;&#xAD11;&#xD559;&#xC744; &#xC0AC;&#xC6A9; &#xD558; &#xC5EC; &#xBE0C;&#xB9AC;&#xC9C0; &#xB9AC;&#xAC04;&#xB4DC;-&#xAE08;&#xC18D; &#xBC0F; Fe-&#xCF5C;&#xB85C;&#xB77C;&#xB3C4; &#xBCA4;&#xB529; &#xC9C4;&#xB3D9;&#xC744; &#xC8FC;&#xC694; &#xAE08;&#xC18D; &#xC218;&#xC18C; &#xBAA8;&#xB4DC;&#xB97C; &#xC2DD;&#xBCC4; &#xD558;&#xB294; &#xB370; &#xC0AC;&#xC6A9; &#xD558;&#xB294; isotopic &#xB300;&#xCCB4;&#xC640; &#xD568;&#xAED8; &#xC2A4;&#xD2B8;&#xB808;&#xCE6D; &#xC9C4;&#xB3D9;&#xC744; &#xAE08;&#xC18D; &#xC218;&#xC18C;&#xB97C; &#xD3EC;&#xD568; &#xD558; &#xC5EC; &#xD604;&#xC7AC; &#xC0AC;&#xC774;&#xD2B8;&#xC758; &#xC9C4;&#xB3D9; &#xBAA8;&#xB4DC; &#xD504;&#xB85C;&#xBE0C;. &#xAE08;&#xC18D; &#xC218;&#xC18C; &#xC9C4;&#xB3D9;&#xACFC; &#xBCF8;&#xC9C8;&#xC801;&#xC73C;&#xB85C; &#xACB0;&#xD569; &#xB41C; &#xB300;&#xD45C; &#xC808;&#xC5F0;, &#xC9C0;&#xC5ED;&#xD654; &#xB41C; &#xC2A4;&#xD2B8;&#xB808;&#xCE6D; &#xBAA8;&#xB4DC;; &#xB2C8;&#xCF08;-&#xC218;&#xC18C; &#xC9C4;&#xB3D9; 945 cm(-1)&#xC5D0;&#xC11C; &#xAD00;&#xCC30; &#xD558;&#xB294; &#xB3D9;&#xC548; &#xCCA0;-&#xC218;&#xC18C; &#xC9C4;&#xB3D9; 1530 cm(-1)&#xC5D0;&#xC11C; &#xBC1C;&#xC0DD; &#xD569;&#xB2C8;&#xB2E4;. &#xAE08;&#xC18D; &#xC218;&#xC18C; &#xC9C4;&#xB3D9; &#xC8FC;&#xD30C;&#xC218;&#xC5D0; &#xB300; &#xD55C; &#xC911;&#xC694; &#xD55C; &#xBAA8;&#xC21C;&#xC774; &#xAE08;&#xC18D; &#xC218;&#xC18C; &#xCC44;&#xAD8C; &#xAE38;&#xC774;&#xC5D0; &#xC57D;&#xAC04;&#xC758; &#xBE44;&#xB300;&#xCE6D;&#xC744; &#xBC18;&#xC601;&#xD569;&#xB2C8;&#xB2E4;. &#xB610;&#xD55C;, &#xC2DC;&#xAC04;&#xC5D0; &#xB530;&#xB77C; &#xBC00;&#xB3C4; &#xBC94;&#xD568;&#xC218; &#xC774;&#xB860; (TD DFT) &#xACC4;&#xC0B0; &#xC774;&#xB7EC;&#xD55C; &#xD654;&#xD569;&#xBB3C;&#xC758; &#xC774;&#xB860;&#xC801;&#xC778; RR &#xC2A4;&#xD399;&#xD2B8;&#xB7FC;&#xC744; &#xC5BB;&#xAE30; &#xC704;&#xD574; &#xC2E4;&#xC2DC; &#xD588;&#xB2E4;. &#xC774;&#xB860;&#xACFC; &#xC2E4;&#xD5D8;&#xC758; &#xC0C1;&#xC138;&#xD55C; &#xBE44;&#xAD50;&#xC5D0; &#xADFC;&#xAC70; &#xD558; &#xC5EC; &#xC9C0;&#xBC30;&#xC801;&#xC778; &#xC804;&#xC790; &#xC804;&#xD658; &#xBC0F; RR &#xC2E4;&#xD5D8;&#xC5D0;&#xC11C; &#xD0D0;&#xC9C0; &#xD558;&#xB294; &#xC911;&#xC694; &#xD55C; &#xC815;&#xC0C1; &#xBAA8;&#xB4DC; &#xD560;&#xB2F9; &#xB41C;; &#xD45C;&#xC2DC; &#xD30C;&#xC7A5;&#xC5D0; &#xAE30;&#xBCF8; &#xC804;&#xD658;&#xC744; &#xAE08;&#xC18D; &#xB300; &#xAE08;&#xC18D; &#xBC0F; &#xAE08;&#xC18D;-&#xB9AC;&#xAC04;&#xB4DC; &#xCDA9;&#xC804; &#xC804;&#xC1A1; &#xBC34;&#xB4DC;&#xB97C; &#xB098;&#xD0C0;&#xB0C5;&#xB2C8;&#xB2E4;. &#xACF5;&#xBA85; &#xB77C;&#xB9CC; &#xC2A4;&#xD399;&#xD2B8;&#xB7FC; &#xBC0F; DFT &#xACC4;&#xC0B0; &#xAE08;&#xC18D; &#xC218;&#xC18C; &#xD3EC;&#xD568; &#xB41C; &#xB2E8;&#xBC31;&#xC9C8;&#xC5D0; &#xC9C4;&#xB3D9; &#xBAA8;&#xB4DC; &#xAC19;&#xC740; &#xAD00;&#xCC30;&#xC758; &#xC804;&#xB9DD;&#xC744; &#xD568;&#xAED8; &#xB17C;&#xC758;&#xC5D0;&#xC11C; &#xAE08;&#xC18D; &#xC218;&#xC18C; &#xC9C4;&#xB3D9; &#xBAA8;&#xB4DC;&#xC758; &#xAE30;&#xBCF8;&#xC801;&#xC778; &#xC18D;&#xC131;. &#xC774;&#xB7EC;&#xD55C; &#xACB0;&#xD569; &#xB41C; &#xC774;&#xB860;&#xC801;&#xC774; &#xACE0; &#xC2E4;&#xD5D8;&#xC801;&#xC778; &#xC811;&#xADFC; [NiFe] hydrogenases&#xC5D0;&#xC11C; &#xC720;&#xC0AC;&#xD55C; redox &#xC2A4;&#xD14C;&#xC774;&#xD2B8;&#xC758; &#xD2B9;&#xC131;&#xD654;&#xC5D0; &#xB300; &#xD55C; &#xAC00;&#xCE58;&#xAC00; &#xC788;&#xC744; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;.

&#xC8FC;&#xC694; &#xD569;&#xAE08; [NiFe] Hydrogenase &#xBAA8;&#xB378; &#xD654;&#xD569;&#xBB3C; &#xACF5;&#xBA85; &#xB77C;&#xB9CC; &#xBD84;&#xAD11;&#xD559; &#xBC0F; &#xBC00;&#xB3C4; &#xAE30;&#xB2A5; &#xACC4;&#xC0B0; &#xD558; &#xC5EC; &#xACF5;&#xBD80;&#xC5D0; &#xC9C4;&#xB3D9; &#xBAA8;&#xB4DC;.

Las prote&iacute;nas de la hidrogenasa catalizan la conversi&oacute;n reversible de hidr&oacute;geno molecular en protones y electrones. Mientras que muchos Estados enzim&aacute;ticos de la hidrogenasa [NiFe] han estudiado extensivamente, hay m&uacute;ltiples catal&iacute;tico EPR-silencioso Estados pertinentes que quedan mal caracterizados. An&aacute;lisis de compuestos modelo utilizando nuevas t&eacute;cnicas espectrosc&oacute;picas pueden proporcionar un marco para el estudio de estos Estados esquivos en la prote&iacute;na. Obtuvimos la resonancia y absorci&oacute;n &oacute;ptica espectros Raman (RR) de (dppe)Ni(&mu;-pdt)Fe(CO)(3) y [(dppe)Ni(&mu;-pdt)(&mu;-H)Fe(CO)(3)][BF(4)], que son compuestos de modelo estructural y funcional para los Estados Ni de EPR-silencioso-SI y Ni-R del sitio activo [NiFe] hidrogenasa. Los estudios presentados aqu&iacute; utilizan espectroscopia RR para modos vibracionales del sitio activo, incluyendo las vibraciones de estiramientos-hidruro junto con bridging ligando-metal y vibraciones de flexi&oacute;n de Fe-CO, con sustituci&oacute;n isot&oacute;pica utilizado para identificar los principales modos de hidruro met&aacute;lico de la sonda. Las vibraciones de hidruro met&aacute;lico son esencialmente desacopladas y representan modos de estiramientos aislados, localizados; la vibraci&oacute;n del hidruro de hierro se produce en 1530 cm(-1), mientras se observa la vibraci&oacute;n de hidruro de n&iacute;quel en 945 cm(-1). La discrepancia significativa entre las frecuencias vibracionales de hidruro de metal refleja la asimetr&iacute;a leve en las longitudes de hidruro met&aacute;lico de bonos. Adem&aacute;s, se realizaron c&aacute;lculos de densidad de time-dependent teor&iacute;a funcional (TD-DFT) para obtener espectros de RR te&oacute;ricos de estos compuestos. Sobre la base de la comparaci&oacute;n detallada de la teor&iacute;a y el experimento, se asignaron los modos normales significativos sondeados en los experimentos de RR y transiciones electr&oacute;nicas dominantes; las transiciones primarias en las longitudes de onda visibles representan bandas de transferencia de carga de metal a metal y metal-a-ligando. Propiedades inherentes de hidruro met&aacute;lico de modos vibracionales en resonancia espectros Raman y c&aacute;lculos de DFT se discuten junto con las perspectivas de observar tales modos vibracionales en prote&iacute;nas que contienen metal-hidruro. Un enfoque te&oacute;rico y experimental tan combinado puede ser valioso para la caracterizaci&oacute;n de Estados redox an&aacute;logo en las hydrogenases [NiFe].

Hidruro clave modos vibracionales en [NiFe] hidrogenasa modelo compuestos estudiados por la espectroscopia de resonancia Raman y densidad funcionales c&aacute;lculos.

Two model compounds of the active site of [NiFe]-hydrogenases with an unusual {S(2)Ni(μ-S)(μ-CO)Fe(CO)(2)S}-coordination environment around the metals are reported. The neutral compound [Ni(xbsms)(μ-CO)(μ-S)Fe(CO)(2)('S')], (1) (H(2)xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) is converted to [1H][BF(4)] by reversible protonation using HBF(4)·Et(2)O. The protonation takes place at the terminal thiolate sulfur atom that is coordinated to nickel. Catalytic intermediates with a protonated terminal cysteinate were suggested for the native protein but have not yet been confirmed experimentally. [1H][BF(4)] is the first dinuclear [NiFe] model compound for such a species. Both complexes have been synthesized and characterized by X-ray crystallography, NMR-, FTIR-, and (57)Fe-Mössbauer spectroscopy as well as by electronic absorption and resonance Raman spectroscopy. The experimental results clearly show that the protonation has a significant impact on the electronic structure of the iron center, although it takes place at the nickel site. DFT calculations support the interpretation of the spectroscopic data and indicate the presence of a bonding interaction between the metal ions, which is relevant for the enzyme as well. Electrochemical experiments show that both 1 and [1H][BF(4)] are active for electrocatalytic proton reduction in aprotic solvents.

A functional [NiFe]-hydrogenase model compound that undergoes biologically relevant reversible thiolate protonation.

Immunoglobulin G (IgG) concentrates have recently been found to be contaminated with procoagulant impurities causing thromboembolic events (TEEs) in vivo. In this study the question was raised whether a thrombin generation assay (TGA) will be able to characterize IgG samples from the Austrian market with regard to their thrombogenic potential.

Assessment of immunoglobulin concentrates on thrombogenic activity by thrombin generation assay, prekallikrein activator assay, and size-exclusion chromatography.

The development of type 1 diabetes (T1D) is potentially influenced by nutrition. The aim of our study was to assess food and nutrient intakes of children at increased risk of T1D.

Evaluating the diet of children at increased risk for type 1 diabetes: first results from the TEENDIAB study.

A series of four [S2Ni(μ-S)2FeCp*Cl] compounds with different tetradentate thiolate/thioether ligands bound to the Ni(II) ion is reported (Cp* = C5Me5). The {S2Ni(μ-S)2Fe} core of these compounds resembles structural features of the active site of [NiFe] hydrogenases. Detailed analyses of the electronic structures of these compounds by Mössbauer and electron paramagnetic resonance spectroscopy, magnetic measurements, and density functional theory calculations reveal the oxidation states Ni(II) low spin and Fe(II) high spin for the metal ions. The same electronic configurations have been suggested for the Cred1 state of the C-cluster [NiFeu] subsite in carbon monoxide dehydrogenases (CODH). The Ni-Fe distance of ∼3 Å excludes a metal-metal bond between nickel and iron, which is in agreement with the computational results. Electrochemical experiments show that iron is the redox active site in these complexes, performing a reversible one-electron oxidation. The four complexes are discussed with regard to their similarities and differences both to the [NiFe] hydrogenases and the C-cluster of Ni-containing CODH.

Modeling the active site of [NiFe] hydrogenases and the [NiFeu] subsite of the C-cluster of carbon monoxide dehydrogenases: low-spin iron(II) versus high-spin iron(II).

Active [FeFe] hydrogenases can be obtained by expressing the unmaturated enzyme in Escherichia coli followed by incubation with a synthetic precursor of the binuclear [2Fe] subcluster, namely: [NEt4]2[Fe2(adt)(CO)4(CN)2] (adt = [S-CH2-NH-CH2-S](2-)). The binuclear subsite Fe2(adt)(CO)3(CN)2 is attached through a bridging cysteine side chain to a [4Fe-4S] subcluster already present in the unmaturated enzyme thus yielding the intact native "H-cluster". We present FTIR electrochemical studies of the [FeFe] hydrogenase from Chlamydomonas reinhardtii, CrHydA1, maturated with the precursor of the native cofactor [Fe2(adt)(CO)4(CN)2](2-) as well as a non-natural variant [Fe2(pdt)(CO)4(CN)2](2-) in which the bridging amine functionality is replaced by CH2. The obtained active enzyme CrHydA1(adt) shows the same redox states in the respective potential range as observed for the native system (E(ox/red) = -400 mV, E(red/sred) = -470 mV). For the Hox → Hred transition the reducing equivalent is stored on the binuclear part, ([4Fe-4S](2+)Fe(II)Fe(I) → [4Fe-4S](2+)Fe(I)Fe(I)), while the Hred → Hsred transition is characterized by a reduction of the [4Fe-4S] part of the H-cluster ([4Fe-4S](2+)Fe(I)Fe(I) → [4Fe-4S](+)Fe(I)Fe(I)). A similar transition is reported here for the CO inhibited state of the H-cluster: ([4Fe-4S](2+)Fe(I)Fe(II)CO → [4Fe-4S](+)Fe(I)Fe(II)CO). An FTIR electrochemical study of the inactive variant with the pdt ligand, CrHydA1(pdt), identified two redox states H(pdt)-ox and H(pdt)-"red". Both EPR and FTIR spectra of H(pdt)-ox are virtually identical to those of the H(adt)-ox and the native Hox state. The H(pdt)-"red" state is also characterized by a reduced [4Fe-4S] subcluster. In contrast to CrHydA1(adt), the H(pdt)-ox state of CrHydA1(pdt) is stable up to rather high potentials (+200 mV). This study demonstrates the distinct redox coupling between the two parts of the H-cluster and confirms that the [4Fe-4S]H subsite is also redox active and as such an integral part of the H-cluster taking part in the catalytic cycle.

New redox states observed in [FeFe] hydrogenases reveal redox coupling within the H-cluster.

[FeFe]-hydrogenases are to date the only enzymes for which it has been demonstrated that the native inorganic binuclear cofactor of the active site Fe2(adt)(CO)3(CN)2 (adt = azadithiolate = [S-CH2-NH-CH2-S](2-)) can be synthesized on the laboratory bench and subsequently inserted into the unmaturated enzyme to yield fully functional holo-enzyme (Berggren, G. et al. (2013) Nature 499, 66-70; Esselborn, J. et al. (2013) Nat. Chem. Biol. 9, 607-610). In the current study, we exploit this procedure to introduce non-native cofactors into the enzyme. Mimics of the binuclear subcluster with a modified bridging dithiolate ligand (thiodithiolate, N-methylazadithiolate, dimethyl-azadithiolate) and three variants containing only one CN(-) ligand were inserted into the active site of the enzyme. We investigated the activity of these variants for hydrogen oxidation as well as proton reduction and their structural accommodation within the active site was analyzed using Fourier transform infrared spectroscopy. Interestingly, the monocyanide variant with the azadithiolate bridge showed ∼50% of the native enzyme activity. This would suggest that the CN(-) ligands are not essential for catalytic activity, but rather serve to anchor the binuclear subsite inside the protein pocket through hydrogen bonding. The inserted artificial cofactors with a propanedithiolate and an N-methylazadithiolate bridge as well as their monocyanide variants also showed residual activity. However, these activities were less than 1% of the native enzyme. Our findings indicate that even small changes in the dithiolate bridge of the binuclear subsite lead to a rather strong decrease of the catalytic activity. We conclude that both the Brønsted base function and the conformational flexibility of the native azadithiolate amine moiety are essential for the high catalytic activity of the native enzyme.

Hybrid [FeFe]-hydrogenases with modified active sites show remarkable residual enzymatic activity.

This study aimed to perform a comprehensive analysis of interlobular, intralobular and parenchymal pancreatic fat in order to assess their respective effects on beta cell function.

Pancreatic adipose tissue infiltration, parenchymal steatosis and beta cell function in humans.

Diamagnetic iron chloro compounds [(P(Ph)2N(Ph)2)FeCp*Cl] [1Cl] and [(P(Cy)2N(Ph)2)FeCp*Cl] [2Cl] and the corresponding hydrido complexes [(P(Ph)2N(Ph)2)FeCp*H] [1H] and [(P(Cy)2N(Ph)2)FeCp*H] [2H] have been synthesized and characterized by NMR spectroscopy, electrochemical studies, electronic absorption, and (57)Fe Mössbauer spectroscopy (P(Ph)2N(Ph)2 = 1,3,5,7-tetraphenyl-1,5-diphospha-3,7-diazacyclooctane, P(Cy)2N(Ph)2 = 1,5-dicyclohexyl-3,7-diphenyl-1,5-diphospha-3,7-diazacyclooctane, Cp* = pentamethylcyclopentadienyl). Molecular structures of [2Cl], [1H], and [2H], derived from single-crystal X-ray diffraction, revealed that these compounds have a typical piano-stool geometry. The results show that the electronic properties of the hydrido complexes are strongly influenced by the substituents at the phosphorus donor atoms of the P(R)2N(Ph)2 ligand, whereas those of the chloro complexes are less affected. These results illustrate that the hydride is a strong-field ligand, as compared to chloride, and thus leads to a significant degree of covalent character of the iron hydride bonds. This is important in the context of possible catalytic intermediates of iron hydrido species, as proposed for the catalytic cycle of [FeFe] hydrogenases and other synthetic catalysts. Both hydrido compounds [1H] and [2H] show enhanced catalytic currents in cyclic voltammetry upon addition of the strong acid trifluoromethanesulfonimide [NHTf2] (pKa(MeCN) = 1.0). In contrast to the related complex [(P(tBu)N(Bn))2FeCp(C6F5)H], which was reported by Liu et al. (Nat. Chem. 2013, 5, 228-233) to be an electrocatalyst for hydrogen splitting, the here presented hydride complexes [1H] and [2H] show the tendency for electrocatalytic hydrogen production. Hence, the catalytic direction of this class of monoiron compounds can be reversed by specific ligand modifications.

Design and Characterization of Phosphine Iron Hydrides: Toward Hydrogen-Producing Catalysts.

Inflammatory processes are involved in the progression of insulin resistance and β-cell dysfunction in individuals with prediabetes and contribute to the development of diabetes. We hypothesized that higher levels of biomarkers of low-grade inflammation are associated with the early progression of recently diagnosed diabetes.

The Role of Markers of Low-Grade Inflammation for the Early Time Course of Glycemic Control, Glucose Disappearance Rate, and β-Cell Function in Recently Diagnosed Type 1 and Type 2 Diabetes.

Article	Year
Glucocorticoid hormone stimulates mitochondrial biogenesis specifically in skeletal muscle. Endocrinology\| PubMed ID: 11751607	2002
Cultivation in glucose-deprived medium stimulates mitochondrial biogenesis and oxidative metabolism in HepG2 hepatoma cells. Biological chemistry\| PubMed ID: 11934266	2002
P-C dichotomy: divergent iron(-I)-mediated alkyne and phosphaalkyne cycloligomerisations. Dalton transactions (Cambridge, England : 2003)\| PubMed ID: 20104301	2010
Key Hydride Vibrational Modes in [NiFe] Hydrogenase Model Compounds Studied by Resonance Raman Spectroscopy and Density Functional Calculations. Inorganic chemistry\| PubMed ID: 23039071	2012
A functional [NiFe]-hydrogenase model compound that undergoes biologically relevant reversible thiolate protonation. Journal of the American Chemical Society\| PubMed ID: 23194246	2012
Assessment of immunoglobulin concentrates on thrombogenic activity by thrombin generation assay, prekallikrein activator assay, and size-exclusion chromatography. Transfusion\| PubMed ID: 23772713	2014
Evaluating the diet of children at increased risk for type 1 diabetes: first results from the TEENDIAB study. Public health nutrition\| PubMed ID: 24476676	2015
Modeling the active site of [NiFe] hydrogenases and the [NiFeu] subsite of the C-cluster of carbon monoxide dehydrogenases: low-spin iron(II) versus high-spin iron(II). Inorganic chemistry\| PubMed ID: 24903610	2014
New redox states observed in [FeFe] hydrogenases reveal redox coupling within the H-cluster. Journal of the American Chemical Society\| PubMed ID: 25025613	2014
Hybrid [FeFe]-hydrogenases with modified active sites show remarkable residual enzymatic activity. Biochemistry\| PubMed ID: 25633077	2015
Pancreatic adipose tissue infiltration, parenchymal steatosis and beta cell function in humans. Diabetologia\| PubMed ID: 25740696	2015
Design and Characterization of Phosphine Iron Hydrides: Toward Hydrogen-Producing Catalysts. Inorganic chemistry\| PubMed ID: 26132460	2015
The Role of Markers of Low-Grade Inflammation for the Early Time Course of Glycemic Control, Glucose Disappearance Rate, and β-Cell Function in Recently Diagnosed Type 1 and Type 2 Diabetes. Diabetes care\| PubMed ID: 26153272	2015

Katharina Weber

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