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Find video protocols related to scientific articles indexed in Pubmed.
NirN Protein from Pseudomonas aeruginosa is a Novel Electron-bifurcating Dehydrogenase Catalyzing the Last Step of Heme d1 Biosynthesis.
J. Biol. Chem.
PUBLISHED: 09-09-2014
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Heme d1 plays an important role in denitrification as the essential cofactor of the cytochrome cd1 nitrite reductase NirS. At present, the biosynthesis of heme d1 is only partially understood. The last step of heme d1 biosynthesis requires a so far unknown enzyme that catalyzes the introduction of a double bond into one of the propionate side chains of the tetrapyrrole yielding the corresponding acrylate side chain. In this study, we show that a Pseudomonas aeruginosa PAO1 strain lacking the NirN protein does not produce heme d1. Instead, the NirS purified from this strain contains the heme d1 precursor dihydro-heme d1 lacking the acrylic double bond, as indicated by UV-visible absorption spectroscopy and resonance Raman spectroscopy. Furthermore, the dihydro-heme d1 was extracted from purified NirS and characterized by UV-visible absorption spectroscopy and finally identified by high-resolution electrospray ionization mass spectrometry. Moreover, we show that purified NirN from P. aeruginosa binds the dihydro-heme d1 and catalyzes the introduction of the acrylic double bond in vitro. Strikingly, NirN uses an electron bifurcation mechanism for the two-electron oxidation reaction, during which one electron ends up on its heme c cofactor and the second electron reduces the substrate/product from the ferric to the ferrous state. On the basis of our results, we propose novel roles for the proteins NirN and NirF during the biosynthesis of heme d1.
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Distinct structural and redox properties of the heme active site in bacterial dye decolorizing peroxidase-type peroxidases from two subfamilies: resonance Raman and electrochemical study.
Biochemistry
PUBLISHED: 04-24-2013
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Spectroscopic data of dye decolorizing peroxidases (DyPs) from Bacillus subtilis (BsDyP), an A subfamily member, and Pseudomonas putida (PpDyP), a B subfamily enzyme, reveal distinct heme coordination patterns of the respective active sites. In solution, both enzymes show a heterogeneous spin population, with the six-coordinated low-spin state being the most populated in the former and the five-coordinated quantum mechanically mixed-spin state in the latter. We ascribe the poor catalytic activity of BsDyP to the presence of a catalytically incompetent six-coordinated low-spin population. The spin populations of the two DyPs are sensitively dependent on the pH, temperature, and physical, i.e., solution versus crystal versus immobilized, state of the enzymes. We observe a redox potential for the Fe(2+)/Fe(3+) couple in BsDyP (-40 mV) at pH 7.6 substantially more positive than those reported for the majority of other peroxidases, including PpDyP (-260 mV). Furthermore, we evaluate the potential of the studied enzymes for biotechnological applications on the basis of electrochemical and spectroelectrochemical data.
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[Relationship between symptoms of obstructive sleep apnea syndrome and traffic accidents in the city drivers].
Tuberk Toraks
PUBLISHED: 04-16-2013
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There is a high tendency for traffic accidents in patients with obstructive sleep apnea syndrome (OSAS). Thus its recommended to investigate OSAS symptoms before certification of professional drivers. However, to what degree OSAS symptoms predict traffic accidents is not clear. We aimed to investigate the relationship between OSAS symptoms and traffic accidents.
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COPD: an underdiagnosed disease at hospital environment.
Wien. Klin. Wochenschr.
PUBLISHED: 03-13-2013
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Chronic obstructive pulmonary disease (COPD) is a serious disease with morbidity and mortality due to delayed diagnosis until significant symptoms arise. We aimed to assess the utility of spirometry and COPD Assessment Test (CAT) in detecting undiagnosed COPD patients in a localized area.
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Percutaneous coronary intervention increases microvascular resistance in patients with non-ST-elevation acute coronary syndrome.
EuroIntervention
PUBLISHED: 02-16-2013
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In the acute coronary syndrome setting, the interaction between epicardial coronary artery stenosis and microcirculation subtended by the culprit vessel is poorly understood. The purpose of the present study was to assess the immediate impact of percutaneous coronary intervention (PCI) on microvascular resistance (MR) in patients with non-ST-elevation myocardial infarction (NSTEMI).
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Role of C-reactive protein in determining microvascular function in patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention.
Am. J. Cardiol.
PUBLISHED: 02-12-2013
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The extent of coronary microvascular dysfunction might be related, not only to patient characteristics and procedural factors, but also to the inflammatory status. The aim of the present study was to examine a possible association between inflammation, as reflected by the serum C-reactive protein (CRP) levels, and the extent of baseline and post-percutaneous coronary intervention (PCI) coronary microvascular dysfunction in patients with non-ST-segment elevation acute coronary syndrome undergoing PCI. A total of 42 patients undergoing PCI for non-ST-segment elevation acute coronary syndrome were enrolled. Coronary microvascular resistance (MR) was determined in the territory of culprit artery using a Doppler probe- and a pressure sensor-equipped guidewire both before (taking the collateral blood into account) and after PCI. The periprocedural changes in MR were calculated. The CRP levels at admission were correlated with the pre-PCI MR (r = 0.498, p = 0.001), post-PCI MR (r = 0.429, p = 0.005), and periprocedural changes in MR (r = 0.785, p <0.001). On multivariate regression analysis, the only predictor of the pre-PCI (? = 0.531, p = 0.002) and post-PCI (? = 0.471, p = 0.012) MR was the serum CRP concentration. Likewise, the periprocedural changes in MR was predicted by the serum CRP levels (? = 0.677, p = 0.001) and the presence of angiographic thrombus (? = -0.275, p = 0.02). In conclusion, these results have shown that the CRP level is related to increased coronary MR in the territory of the culprit lesion. This suggests that inflammatory processes might play a role in microvascular impairment in patients with non-ST-segment elevation acute coronary syndrome.
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Role of the HoxZ subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase from Ralstonia eutropha immobilized on electrodes.
J Phys Chem B
PUBLISHED: 08-09-2011
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The role of the diheme cytochrome b (HoxZ) subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase (MBH) heterotrimer from Ralstonia eutropha H16 has been investigated. The MBH in its native heterotrimeric state was immobilized on electrodes and subjected to spectroscopic and electrochemical analysis. Surface enhanced resonance Raman spectroscopy was used to monitor the redox and coordination state of the HoxZ heme cofactors while concomitant protein film voltammetric measurements gave insights into the catalytic response of the enzyme on the electrode. The entire MBH heterotrimer as well as its isolated HoxZ subunit were immobilized on silver electrodes coated with self-assembled monolayers of ?-functionalized alkylthiols, displaying the preservation of the native heme pocket structure and an electrical communication between HoxZ and the electrode. For the immobilized MBH heterotrimer, catalytic reduction of the HoxZ heme cofactors was observed upon H(2) addition. The catalytic currents of MBH with and without the HoxZ subunit were measured and compared with the heterogeneous electron transfer rates of the isolated HoxZ. On the basis of the spectroscopic and electrochemical results, we conclude that the HoxZ subunit under these artificial conditions is not primarily involved in the electron transfer to the electrode but plays a crucial role in stabilizing the enzyme on the electrode.
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Resting metabolic rate and anthropometric measurements in male sleep apnea patients.
Intern. Med.
PUBLISHED: 04-15-2011
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Obstructive Sleep Apnea Syndrome (OSAS) is a common sleep-related breathing disorder. Associations among Apnea-Hypopnea Index (AHI), Resting Metabolic Rate (RMR), body habitus differences, and otorhinolaryngologic abnormality may clarify the characteristics of patients with OSAS. In order to test this hypothesis, we aimed to compare the RMR, Modified Mallampati Scores (MMS), anthropometric measurements and body composition of male OSAS patients with simple snorers and to investigate the association among these parameters.
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Surface-enhanced vibrational spectroscopy for probing transient interactions of proteins with biomimetic interfaces: electric field effects on structure, dynamics and function of cytochrome c.
FEBS J.
PUBLISHED: 03-22-2011
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Most of the biochemical and biophysical processes of proteins take place at membranes, and are thus under the influence of strong local electric fields, which are likely to affect the structure as well as the reaction mechanism and dynamics. To analyse such electric field effects, biomimetic interfaces may be employed that consist of membrane models deposited on nanostructured metal electrodes. For such devices, surface-enhanced resonance Raman and IR absorption spectroscopy are powerful techniques to disentangle the complex interfacial processes of proteins in terms of rotational diffusion, electron transfer, and protein and cofactor structural changes. The present article reviews the results obtained for the haem protein cytochrome c, which is widely used as a model protein for studying the various reaction steps of interfacial redox processes in general. In addition, it is shown that electric field effects may be functional for the natural redox processes of cytochrome c in the respiratory chain, as well as for the switch from the redox to the peroxidase function, one of the key events preceding apoptosis.
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Functionalized Ag nanoparticles with tunable optical properties for selective protein analysis.
Chem. Commun. (Camb.)
PUBLISHED: 02-15-2011
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We present a preparation procedure for small sized biocompatibly coated Ag nanoparticles with tunable surface plasmon resonances. The conditions were optimised with respect to the resonance Raman signal enhancement of heme proteins and to the preservation of the native protein structure.
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The accuracy of deceleration time of diastolic coronary flow measured by transthoracic echocardiography in predicting long-term left ventricular infarct size and function after reperfused myocardial infarction.
Eur J Echocardiogr
PUBLISHED: 06-30-2010
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Assessment of microvascular function after reperfused acute myocardial infarction (AMI) provides important insights for myocardial reperfusion and facilitates prediction of long-term left ventricular (LV) function and clinical outcome. In this study, we examined microvascular integrity 48 h after successful primary percutaneous coronary intervention (PCI) and compared predictive accuracy of the intracoronary pressure-wire- and transthoracic Doppler echocardiography-based parameters in the estimation of long-term LV infarct size and function.
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Multi-layer electron transfer across nanostructured Ag-SAM-Au-SAM junctions probed by surface enhanced Raman spectroscopy.
Phys Chem Chem Phys
PUBLISHED: 06-11-2010
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We have developed a new layered Au-Ag electrode for studying interfacial electron transfer processes by surface enhanced resonance Raman (SERR) spectroscopy. The device consists of a nanostructured Ag support which is separated from a Au film via a thin self-assembled monolayer (SAM) of amino-terminated mercaptanes (C(y)-NH(2), with y = 6, 8, 11). The Au film is biocompatibly coated to allow for binding of redox-active proteins. We have explored the performance of this device for analysing interfacial electron transfer processes by stationary and time-resolved SERR spectroscopy, using the heme protein cytochrome c (Cyt-c) as a benchmark protein. The SERRS intensity of Cyt-c on Ag-(C(y)-NH(2))-Au electrodes and Ag electrodes was comparable when the protein was electrostatically attached to the metal coated by a SAM of carboxyl-terminated mercaptanes (C(x)-COOH) surface but 25 times higher upon covalent attachment via Cys102 to the bare Au surface. In the case of electrostatic adsorption the protein remained exclusively in its native state. Electron transfer between the protein and the Ag electrode occurred in an almost ideal Nernstian behaviour with a number of transferred electrons close to one (n = 0.8-0.9). Conversely, the covalent attached Cyt c showed two broad redox transitions (n = 0.3) and a partial conversion to a non-native species which remained redox inactive in the potential range from +0.1 to -0.3 V. For the electrostatically immobilised Cyt, apparent electron transfer rates of 0.8 and 49 s(-1) were obtained for y = 11 and x = 15 and 10, respectively, indicating a fast long-distance electron transfer through the multilayer with the electron tunneling through the C(x)-COOH SAM being the rate limiting step.
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Redox properties and catalytic activity of surface-bound human sulfite oxidase studied by a combined surface enhanced resonance Raman spectroscopic and electrochemical approach.
Phys Chem Chem Phys
PUBLISHED: 05-26-2010
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Human sulfite oxidase (hSO) was immobilised on SAM-coated silver electrodes under preservation of the native heme pocket structure of the cytochrome b5 (Cyt b5) domain and the functionality of the enzyme. The redox properties and catalytic activity of the entire enzyme were studied by surface enhanced resonance Raman (SERR) spectroscopy and cyclic voltammetry (CV) and compared to the isolated heme domain when possible. It is shown that heterogeneous electron transfer and catalytic activity of hSO sensitively depend on the local environment of the enzyme. Increasing the ionic strength of the buffer solution leads to an increase of the heterogeneous electron transfer rate from 17 s(-1) to 440 s(-1) for hSO as determined by SERR spectroscopy. CV measurements demonstrate an increase of the apparent turnover rate for the immobilised hSO from 0.85 s(-1) in 100 mM buffer to 5.26 s(-1) in 750 mM buffer. We suggest that both effects originate from the increased mobility of the surface-bound enzyme with increasing ionic strength. In agreement with surface potential calculations we propose that at high ionic strength the enzyme is immobilised via the dimerisation domain to the SAM surface. The flexible loop region connecting the Moco and the Cyt b5 domain allows alternating contact with the Moco interaction site and the SAM surface, thereby promoting the sequential intramolecular and heterogeneous electron transfer from Moco via Cyt b5 to the electrode. At lower ionic strength, the contact time of the Cyt b5 domain with the SAM surface is longer, corresponding to a slower overall electron transfer process.
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Concurrent microvascular and infarct remodeling after successful reperfusion of ST-elevation acute myocardial infarction.
Circ Cardiovasc Interv
PUBLISHED: 05-18-2010
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Connection between the course of microvascular and infarct remodeling processes over time after reperfused ST-elevation acute myocardial infarction has not been fully elucidated. The aim of this study is to investigate the association of temporal changes in hemodynamics of microcirculation in the infarcted territory and infarct size (IS) after primary percutaneous coronary intervention in patients with ST-elevation acute myocardial infarction.
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Infarct remodeling process during long-term follow-up after reperfused acute myocardial infarction.
Am. J. Med. Sci.
PUBLISHED: 11-04-2009
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After acute myocardial infarction (AMI), the recovery of perfusion in infarct area may lead to significant spontaneous infarct size (IS) reduction during the subsequent period. The natural course of infarct-healing process after reperfusion therapy has not been fully elucidated. In this study, we investigated the time course of the spontaneous infarct-healing process in patients with reperfused AMI.
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Aerobic and anaerobic exercise capacities in obstructive sleep apnea and associations with subcutaneous fat distributions.
Lung
PUBLISHED: 04-08-2009
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Obesity is a strong risk factor for the development and progression of sleep apnea. Responses to exercise by patients with obstructive sleep apnea syndrome (OSAS) are clinically relevant to reducing body weight and cardiovascular risk factors. This study aimed to clarify the aerobic and anaerobic exercise capacities and their possible relationships with other findings in patients with OSAS. Forty patients (30 males, 10 females) and 40 controls (30 males, 10 females) were enrolled in this study. Questionnaires (excessive daytime sleepiness, daytime tiredness, morning headache, waking unrefreshed, and imbalance), overnight polysomnography, indirect laryngoscopy, and aerobic and anaerobic exercise tests were performed. Triceps, subscapular, abdomen, and thigh skinfold thicknesses were measured. Subcutaneous abdominal fat (abdomen skinfold) was significantly higher in OSAS patients than in controls. Maximal anaerobic power and anaerobic capacity were not different significantly between the patients and controls. We found that aerobic capacity was significantly lower in OSAS patients than in controls. Aerobic capacity was negatively correlated with upper-body subcutaneous fat (triceps and subscapular skinfolds) but not correlated with subcutaneous abdominal fat in OSAS patients. In multivariate analyses using all patients, the apnea-hypopnea index remained a significant independent predictor of aerobic capacity after controlling for a variety of potential confounders including body mass index. Our data confirm that central obesity (subcutaneous abdominal fat) is prominent in patients with OSAS. Our results suggest that lower aerobic exercise capacity in patients with OSAS might be due to daily physical activity that is restricted by OSA itself. This study also suggests that the degree of subcutaneous abdominal fat cannot be used for predicting aerobic capacity level. We think that upper-body subcutaneous fat might be suitable for determining the physical fitness of patients with OSAS.
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Novel Au-Ag hybrid device for electrochemical SE(R)R spectroscopy in a wide potential and spectral range.
Nano Lett.
PUBLISHED: 03-31-2009
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A nanostructured gold-silver-hybrid electrode for SER spectroelectrochemistry was developed which advantageously combines the electrochemical properties and chemical stability of Au and the strong surface enhancement of (resonance) Raman scattering by Ag. The layered device consists of a massive nanoscopically rough Ag electrode, a thin (2 nm) organic layer, and a ca. 20 nm thick Au film that may be coated by self-assembled monolayers for protein adsorption. The SERR-spectroscopic and electrochemical performance of this device is demonstrated using the heme protein cytochrome c as a benchmark model system, thereby extending, for the first time, SE(R)R studies of molecules on Au surfaces to excitation in the violet spectral range. The enhancement factor is only slightly lower than for Ag electrodes which can be rationalized in terms of an efficient transfer of plasmon resonance excitation from the Ag to the Au coating. This mechanism, which requires a thin dielectric layer between the two metals, is supported by theoretical calculations.
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A neck mass with brachial plexus injury: Potts disease.
Am J Otolaryngol
PUBLISHED: 03-06-2009
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Tuberculous osteomyelitis of the spine is most commonly seen in lower thoracic and lumbar vertebrae. Cervical spine tuberculosis is a very rare condition, and it represents a very small part of all patients with Potts disease. We present a case with thoraco-cervical Potts disease, with left-sided neck mass and left arm and hand weakness and numbness. The patient had a paraspinal abscess under the sternocleidomastoid muscle that was compressing the brachial plexus.
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Effect of intracoronary streptokinase administered immediately after primary percutaneous coronary intervention on long-term left ventricular infarct size, volumes, and function.
J. Am. Coll. Cardiol.
PUBLISHED: 01-20-2009
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The purpose of this study was to investigate the reflections of the improvement in microvascular perfusion provided by adjuvant intracoronary streptokinase (ICSK) on late-phase infarct size and left ventricular volumes and functions.
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Design of a peptidic turn with high affinity for Hg(II).
Inorg Chem
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A four amino acid peptide containing the ?-turn template dPro-Pro in the middle and two cysteines (Cys) in the terminal positions (CdPPC) has been synthesized and its mercury(II) coordination properties studied using different spectroscopic methods. The UV-vis, CD, (199m)Hg PAC, and Raman spectroscopic studies indicate the binding of Hg(II) to the two Cys, forming the dithiolatemercury(II) complex Hg(CdPPC). Electrospray ionization mass spectrometry corroborates the 1:1 complex formation. A log K = 40.0 was determined for the formation constant of the Hg(CdPPC) complex using competition potentiometric studies. Replacement of the dPro-Pro motif by a Pro-Pro unit generated a peptide (CPPC) capable of forming a similar species [Hg(CPPC)] but showing a lower affinity for Hg(II) (at least 3-3.5 orders of magnitude lower). The introduction of the dPro-Pro motif is crucial to induce the folding of the CdPPC peptide into a ?-turn, preorganizing the two Cys for mercury(II) coordination. While the simple dPro-Pro unit mimics the overall preorganization achieved by the protein scaffold in metalloproteins containing the conserved metal ion chelation unit CXXC, the high thiophilicity of this metal stabilizes the final complex in a wide pH range (1.1-10). Using computational modeling, the structures of two conformers for Hg(CdPPC) have been optimized that differ mainly in the orientation of the plane containing S-Hg-S with respect to the anchoring C atoms.
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Severe thrombocytopenia and alveolar hemorrhage represent two types of bleeding tendency during tirofiban treatment: case report and literature review.
Int. J. Hematol.
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Tirofiban is a glycoprotein (GP) IIb/IIIa receptor antagonist used in the treatment of acute coronary syndrome (ACS). Thrombocytopenia is a well-known complication of GPIIb/IIIa inhibitors. Life-threatening complications such as alveolar and gastrointestinal system hemorrhages may occur in the course of thrombocytopenia. Platelet count should be monitored closely, including during the first few hours of the infusion. Adverse events may be prevented by prompt discontinuation of the therapy. Herein we present two cases of profound and sudden thrombocytopenia associated with tirofiban use in the treatment of ACS together with a review of the literature.
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Analyzing the catalytic processes of immobilized redox enzymes by vibrational spectroscopies.
IUBMB Life
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Analyzing the structure and function of redox enzymes attached to electrodes is a central challenge in many fields of fundamental and applied life science. Electrochemical techniques such as cyclic voltammetry which are routinely used do not provide insight into the molecular structure and reaction mechanisms of the immobilized proteins. Surface-enhanced infrared absorption (SEIRA) and surface-enhanced resonance Raman (SERR) spectroscopy may fill this gap, if nanostructured Au or Ag are used as conductive support materials. In this account, we will first outline the principles of the methodology including a description of the most important strategies for biocompatible protein immobilization. Subsequently, we will critically review SERR and SEIRA spectroscopic approaches to characterize the protein and active site structure of the immobilized enzymes. Special emphasis is laid on the combination of surface-enhanced vibrational spectroscopies with electrochemical methods to analyze equilibria and dynamics of the interfacial redox processes. Finally, we will assess the potential of SERR and SEIRA spectroscopy for in situ investigations on the basis of the first promising studies on human sulfite oxidase and hydrogenases under turnover conditions.
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Adsorption of sulfite oxidase on self-assembled monolayers from molecular dynamics simulations.
Langmuir
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Sulfite oxidase (SO) is an enzyme catalyzing the terminal step of the metabolism of sulfur-containing amino acids that is essential for almost all living organisms. The catalytic activity of SO in vertebrates strongly depends on the efficiency of the intramolecular electron transfer (IET) between the catalytic Moco domain and the cytochrome b5 (cyt b5) domain. The IET process is assumed to be mediated by large domain motions of the cyt b5 domains within the enzyme. Thus, the interaction of SO with charged surfaces may affect the mobility of the cyt b5 domain required for IET and consequently hinder SO activation. In this study, we present a molecular dynamics approach to investigating the ionic strength dependence of the initial surface adsorption of SO in two different conformations-the crystallographic structure and the model structure for an activated SO-onto mixed amino- and hydroxyl-terminated SAMs. The results show for both conformations at low ionic strengths a strong adsorption of the cyt b5 units onto the SAM, which inhibits the domain motion event required for IET. Under higher ion concentrations, however, the interaction with the surface is weakened by the negatively charged ions acting as a buffer and competing in adsorption with the cathodic cyt b5 domains. This competition prevents the immobilization of the cytochrome b5 units onto the surface, allowing the intramolecular domain motions favoring IET. Our predictions support the interpretation of recent experimental spectroelectrochemical studies on SO.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.