Name: how protein shape determines function
Uploaded: 2023-04-30T18:28:47.000Z
Duration: 2 min 15 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-1

Protein and Protein Structures

Eiwitten zijn polymeren van aminozuren die via peptidebindingen met elkaar zijn verbonden. De meeste eiwitten vouwen zich in specifieke driedimensionale structuren om hun functie uit te voeren. De eiwitstructuur is ingedeeld in vier categorieën:primair, secundair, tertiair en quartair.De lineaire opeenvolging van aminozuren in het eiwit is de primaire structuur. Deze sequenties worden gelezen in de volgorde van polymeersynthese, van het N-uiteinde, het vrije amino-uiteinde, tot het C-uiteinde, het vrije carboxyluiteinde. Secundaire structuren ontstaan door waterstofbinding tussen de zuurstof uit de carbonylgroep van het ene aminozuur en de waterstof uit de aminogroep van een ander.Veel voorkomende secundaire structuren zijn α-helices en β-platen. Deze en andere verbindende structuren, zoals β-bochten, werken verder samen om de driedimensionale structuur van het eiwit te vormen, bekend als de tertiaire structuur. De vorming van de tertiaire structuur vindt plaats door interacties tussen de R-groepen van de aminozuren.R-groepen met tegengestelde ladingen kunnen ionische bindingen vormen en zwavel in twee cysteïnen kan een covalente disulfidebrug vormen. Andere bijdragen zijn onder meer hydrofobe interacties tussen hydrofobe zijketens en waterstofbruggen tussen polaire zijketens. Bovendien vormen sommige eiwitten quaternaire structuren, samenstellingen van twee of meer polypeptideketens.Hemoglobine is bijvoorbeeld een eiwit dat bestaat uit vier subeenheden, twee α en twee β. Wetenschappers kunnen de structuur van een eiwit gebruiken om zijn functie en locatie in een cel te voorspellen. Eiwitten in het celcytoplasma hebben hydrofiele aminozuren op hun oppervlak die een wisselwerking hebben met het water in het cytoplasma en hydrofobe kernen hebben.Eiwitten die in celmembranen aanwezig zijn, hebben daarentegen vaak hydrofobe aminozuren op het oppervlak die een interactie aangaan met glycerofosfolipiden in het membraan en hebben hydrofiele kernen.

protein and protein structures

Eiwitten zijn een van de meest voorkomende organische moleculen in levende systemen en hebben de meest uiteenlopende functies van alle macromoleculen. Eiwitten kunnen structureel, regulerend, contractiel of beschermend zijn. Ze kunnen dienen bij transport, opslag of membranen; of het kunnen toxinen of enzymen zijn. Hun structuren variëren, net als hun functies, enorm. Het zijn echter allemaal aminozuurpolymeren die in een lineaire volgorde zijn gerangschikt. De vorm van een eiwit is van cruciaal belang voor zijn functie. Een enzym kan bijvoorbeeld een specifiek substraat op zijn actieve plaats binden. Als deze actieve plaats wordt gewijzigd vanwege lokale veranderingen of veranderingen in de algehele eiwitstructuur, kan het enzym mogelijk niet aan het substraat binden. Om te begrijpen hoe het eiwit zijn uiteindelijke vorm of conformatie krijgt, moeten we de vier niveaus van de eiwitstructuur begrijpen: primair, secundair, tertiair en quaternair. Primaire structuur De unieke sequentie van aminozuren in een polypeptideketen is de primaire structuur ervan. Het pancreashormoon insuline heeft bijvoorbeeld twee polypeptideketens, A en B, en deze zijn met elkaar verbonden door disulfidebindingen. Het N-terminale aminozuur van de A-keten is glycine; terwijl het C-terminale aminozuur asparagine is. De aminozuursequenties in de A- en B-ketens zijn uniek voor insuline. Het gen dat voor het eiwit codeert, bepaalt uiteindelijk de unieke sequentie voor elk eiwit. Een verandering in de nucleotidesequentie van het coderende gebied van het gen kan leiden tot het toevoegen van een ander aminozuur aan de groeiende polypeptideketen, waardoor een verandering in de eiwitstructuur en -functie ontstaat. Bij sikkelcelanemie heeft de β-keten van hemoglobine een enkele aminozuursubstitutie, waardoor een verandering in de eiwitstructuur en -functie ontstaat. Specifiek vervangt valine in de β-keten het aminozuur glutaminezuur. Vanwege deze verandering van één aminozuur in de keten vormen hemoglobinemoleculen lange vezels die de biconcave of schijfvormige rode bloedcellen vervormen en ervoor zorgen dat ze een halvemaan- of sikkelvorm aannemen, waardoor de bloedvaten verstopt raken. Dit kan leiden tot talloze ernstige gezondheidsproblemen, zoals kortademigheid, duizeligheid, hoofdpijn en buikpijn voor degenen die aan deze ziekte lijden. Secundaire structuur De lokale vouwing van het polypeptide in sommige regio's geeft aanleiding tot de secundaire structuur van het eiwit. De meest voorkomende zijn de α-helix- en β-geplooide plaatstructuren. Beide structuren worden in vorm gehouden door waterstofbruggen. De waterstofbruggen vormen zich tussen het zuurstofatoom in de carbonylgroep in het ene aminozuur en een ander aminozuur dat vier aminozuren verder in de keten ligt. Elke spiraalvormige winding in een alfa-helix heeft 3,6 aminozuurresiduen. De R-groepen van het polypeptide (de variantgroepen) steken uit de a-helixketen. In het β-geplooide vel vormt de waterstofbinding tussen atomen op de ruggengraat van de polypeptideketen de "plooien". De R-groepen zijn aan de koolstofatomen bevestigd en strekken zich uit boven en onder de vouwen van de plooi. De geplooide segmenten zijn parallel of antiparallel aan elkaar uitgelijnd, en er vormen zich waterstofbruggen tussen het gedeeltelijk positieve waterstofatoom in de aminogroep en het gedeeltelijk negatieve zuurstofatoom in de carbonylgroep van de peptideskelet. De α-helix en β-geplooide plaatstructuren bevinden zich in de meeste bolvormige en vezelachtige eiwitten en spelen een belangrijke structurele rol. Tertiaire structuur De unieke driedimensionale structuur van het polypeptide is de tertiaire structuur. Deze structuur is gedeeltelijk te wijten aan chemische interacties die aan de polypeptideketen werken. In de eerste plaats creëren de interacties tussen R-groepen de complexe driedimensionale tertiaire structuur van het eiwit. De aard van de R-groepen in de betrokken aminozuren kan de vorming van de waterstofbruggen die we beschreven hebben voor standaard secundaire structuren tegenwerken. R-groepen met gelijke ladingen stoten elkaar bijvoorbeeld af, en groepen met ongelijke ladingen worden tot elkaar aangetrokken (ionische bindingen). Wanneer eiwitvouwing plaatsvindt, liggen de hydrofobe R-groepen van de niet-polaire aminozuren in het binnenste van het eiwit; terwijl de hydrofiele R-groepen aan de buitenkant liggen. Interacties tussen cysteïnezijketens vormen disulfidebindingen in aanwezigheid van zuurstof, de enige covalente binding die ontstaat tijdens het vouwen van eiwitten. Al deze interacties, zwak en sterk, bepalen de uiteindelijke driedimensionale vorm van het eiwit. Wanneer een eiwit zijn driedimensionale vorm verliest, is het mogelijk niet langer functioneel. Quaternaire structuur In de natuur worden sommige eiwitten gevormd uit verschillende polypeptiden of subeenheden, en de interactie van deze subeenheden vormt de quaternaire structuur. Zwakke interacties tussen de subeenheden helpen de algehele structuur te stabiliseren. Insuline (een bolvormig eiwit) heeft bijvoorbeeld een combinatie van waterstof- en disulfidebindingen waardoor het grotendeels in een bolvorm klontert. Insuline begint als een enkel polypeptide en verliest enkele interne sequenties in de aanwezigheid van post-translationele modificatie na het vormen van de disulfidebindingen die de resterende ketens bij elkaar houden. Zijde (een vezelachtig eiwit), hoe ooit heeft een β-geplooide plaatstructuur die het resultaat is van waterstofbinding tussen verschillende ketens. Deze tekst is aangepast van <a href="https://openstax.org/books/biology-2e/pages/3-4-proteins">Openstax, Biology 2e, Hoofdstuk 3.4: Eiwitten</a>.

Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may ...

Education

JoVE Core

Cell Biology

Celbiologie

Unit 1

Eenheid 1

Biochemistry of the Cell

Biochemie van de cel

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Eiwit en Eiwitstructuren

how protein shape determines function

Proteins are essential molecules in living things, and their shape affects how they work. Protein structure is described at several levels, including primary, secondary, tertiary, and quaternary structure. These levels help explain how a protein is built and how its final form supports its job.

Primary structure is the sequence of amino acids in a protein. Secondary structure forms when parts of the chain fold into regular patterns. Tertiary structure is the overall three-dimensional shape of one protein chain. Quaternary structure appears when more than one protein chain joins together to make a working protein.

The video also shows how protein structure can be represented in different ways. A simple line drawing can show the amino acid sequence. Other models can show folding and the full 3D shape. These visual forms help students compare levels of structure and see why protein shape matters.

How Protein Shape Determines Function

the periodic table and organismal elements

the-periodic-table-and-organismal-elements

Elements in the Human Body and Periodic Table

Elements are the smallest units of matter that cannot be broken down further by chemical processes. Scientists know 118 elements, but not all of them occur naturally. Only a small number are essential for life, and living matter depends mostly on carbon, nitrogen, hydrogen, and oxygen. The periodic table organizes elements by their physical and chemical properties. Each square shows the element name, chemical symbol, atomic number, and atomic weight. The atomic number is the number of protons...

functional groups

Functional Groups in Organic Molecules

Functional groups are the part of an organic molecule that gives it specific chemical behavior. They help explain why compounds with similar carbon skeletons can react in different ways. In organic chemistry, these groups are often used to classify compounds. A functional group can change the properties of a molecule and affect how it behaves in a reaction. Knowing functional groups helps students recognize patterns in organic compounds. It also makes it easier to compare molecules that share...

types of chemical bonds

Chemical Bonds and How Atoms Join

Chemical bonds hold atoms together and help explain how different substances form. In chemistry, the main bond types are ionic bonds, covalent bonds, and metallic bonds. Ionic bonds form when electrons move from one atom to another. Covalent bonds form when atoms share electrons. Metallic bonds occur in metals, where electrons are held in a shared arrangement that gives metals their characteristic behavior. Understanding these bond types helps students compare how atoms connect in different...

noncovalent attractions in biomolecules

Biomolecule Interactions Without Covalent Bonds

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polymers

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structure of lipids

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chemistry of carbohydrates

Carbohydrate Structure and Bonding

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nucleic acids

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Proteins are essential molecules in living things, and their shape affects how they work. Protein structure is described at several levels, including primary, secondary, tertiary, and quaternary structure. These levels help explain how a protein is built and how its final form supports its job. Primary structure is the sequence of amino acids in a protein. Secondary structure forms when parts of the chain fold into regular patterns. Tertiary structure is the overall three-dimensional shape of...

ph regulation in cells

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chemistry of the cell

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Cell chemistry explains the substances that make cells work. Water is the main component of cells, and it supports the chemical reactions that keep life going. Cells also contain organic molecules, which are carbon-based compounds, and inorganic ions, which are charged particles needed for cell function. Organic molecules in cells include carbohydrates, lipids, proteins, and nucleic acids. These molecules have different roles, but together they build cell structures, store energy, and carry...

key terms and concepts

Learn how proteins are built and folded through primary, secondary, tertiary, and quaternary structure, and how protein shape affects function.

How Protein Shape Determines Function | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Florida Department of Education

SC.912.L.18

SC.912.L.18.1

SC.912.L.18.4

new-york-state-science-learning-standards

New York State Science Learning Standards

Structure and Function

HS-LS1-1.

Georgia Standards of Excellence

9-12

Biology

SB6.c

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

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Mechanical Protein Function

Structural Protein Function

Protein Networks

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. [Assessment Boundary: Assessment does not include identification of specific cell or tissue types, whole body systems, specific protein structures and functions, or the biochemistry of protein synthesis.]

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Blood Withdrawal II

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Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. [Clarification Statement: Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, and organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.] [Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction level.]

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How Protein Shape Determines Function

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