Name: how enzymes adjust to their substrates
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 1 min 13 s
Channel: JoVE

- [Instructeur] Enzymen, die meestal eiwitten zijn, werken door zich te binden aan een substraat, een molecuul waarop ze werken en waarvoor ze specifiek zijn. Dit betekent dat ze zich alleen aan bepaalde substraten kunnen binden. Deze eigenschap wordt voornamelijk bepaald door de vorm en de chemische eigenschappen van hun actieve plaats, het gebied van het enzym dat zich aan het substraat bindt.

In overeenstemming met het geïnduceerde model van enzymactiviteit verandert deze binding de bevestiging, de vorm van zowel het enzym als het substraat. Dit brengt het substraat dichter bij de hogere energietransitietoestand die nodig is om de reactie te laten plaatsvinden. Bijvoorbeeld door haar banden te verzwakken, zodat het sneller kan reageren. Nadat het product van de reactie is geproduceerd, komt het enzym vrij en kan het gebruikt worden om reacties opnieuw te katalyseren.

model met geïnduceerde pasvorm

Induced-fit Model

De meeste chemische reacties in cellen vereisen enzymen – biologische katalysatoren die de reactie versnellen zonder te worden verbruikt of permanent te worden veranderd. Enzymen verlagen de activeringsenergie die nodig is om reactanten om te zetten in producten. Enzymen zijn eiwitten die meestal werken door zich te binden aan een substraat – een reactantmolecuul waarop ze inwerken.

Enzymen vertonen substraatspecificiteit, wat betekent dat ze alleen aan bepaalde substraten kunnen binden. Dit wordt voornamelijk bepaald door de vorm en chemische kenmerken van hun actieve plaats – het gebied van het enzym dat zich aan het substraat bindt.

Volgens het geïnduceerde-fit model van enzymactiviteit veroorzaakt deze binding een conformatieverandering (vormverandering) in het enzym. Dit brengt het substraat dichter bij de hogere energietransitietoestand die nodig is om de reactie te laten plaatsvinden. Bijvoorbeeld, het enzym kan de bindingen in het substraat verzwakken, waardoor de reactie gemakkelijker kan verlopen. Daarnaast kunnen enzymen de reactie versnellen door binnen de actieve plaats specifieke chemische omstandigheden te creëren die gunstiger zijn voor de reactie dan in de omringende cellulaire omgeving.

Zodra de producten van de reactie zijn gevormd, worden ze vrijgegeven uit de actieve plaats van het enzym, waarna het enzym opnieuw reacties kan katalyseren.

Model met geïnduceerde pasvorm

Most chemical reactions in cells require enzymes&#8212;biological catalysts that speed up the reaction without being consumed or permanently changed. They ...

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how enzymes adjust to their substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products.

Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical features of the enzyme’s active site, the region that binds the substrate.

The induced-fit model explains what happens after the substrate binds. The binding changes the enzyme’s shape, or conformation. This change helps bring the substrate closer to the higher-energy transition state needed for the reaction, such as by weakening bonds so the substrate can react more easily.

Enzymes can also make the active site a better place for the reaction than the surrounding cell environment. After the products form, they leave the active site. The enzyme can then catalyze the reaction again.

How Enzymes Adjust to Their Substrates

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key terms and concepts

Learn how enzyme active sites change shape in the induced-fit model, helping substrates reach the transition state and reactions happen faster.

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How Enzymes Adjust to Their Substrates

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