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

- [Istruttore] Gli enzimi,
che di solito sono proteine,

lavorano legandosi ad un substrato,

una molecola su cui agiscono

e per la quale hanno una specificità.

Significa che possono legarsi
solo a determinati substrati.

Questa proprietà è determinata
principalmente dalla forma

e dalle caratteristiche
chimiche del loro sito attivo,

la regione dell'enzima
che si lega al substrato.

Conforme con il modello ad induzione

dell'attività enzimatica,
questo legame cambia

la conformazione, la forma,

sia dell'enzima che del substrato.

Questo porta il substrato più vicino

allo stato di transizione
energetica superiore

necessaria perché la
reazione si verifichi.

Per esempio, indebolendo i suoi legami

in modo che possa reagire più prontamente.

Dopo che il prodotto
della reazione è prodotto,

l'enzima viene rilasciato
e può essere utilizzato

per catalizzare di nuovo le reazioni.

modello chiave-serratura

Induced-fit Model

La maggior parte delle reazioni chimiche nelle cellule richiedono enzimi, ovvero catalizzatori biologici che accelerano la reazione senza essere esauriti o permanentemente cambiati. Funzionano riducendo l'energia di attivazione necessaria affinché i reagenti possano essere convertiti nei prodotti. Gli enzimi, che di solito sono proteine, funzionano legandosi a un substrato, una molecola di reazione su cui agiscono.

<h4>Specificità</h4>

Gli enzimi presentano specificità del substrato, il che significa che possono legarsi solo a determinati substrati. Questo è determinato principalmente dalla forma e dalle caratteristiche chimiche del loro sito attivo, la regione dell'enzima che si lega al substrato.

Secondo il modello indotto dell'attività degli enzimi, questo legame modifica la conformazione, o forma, sia dell'enzima che del substrato. Questo porta il substrato più vicino allo stato di transizione energetica superiore necessario affinché la reazione si verifichi, ad esempio indebolendo i suoi legami in modo che possa reagire più facilmente. Gli enzimi possono anche accelerare una reazione creando condizioni all'interno del sito attivo che sono più favorevoli per la reazione di procedere rispetto all'ambiente cellulare circostante.

Una volta che i prodotti della reazione sono formati, vengono rilasciati dal sito attivo e l'enzima può essere utilizzato per catalizzare le reazioni ancora una volta.

Modello chiave-serratura

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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