Mechanism of Enzyme

Induced fit mechanism

The active site is not complementary to the substrate
But the active site of enzyme is flexible and can change the active site during reaction
When collision occurs btw enzyme and substrate, substrate can bind to the active site of enzyme
The binding site of substate induces the enzyme to change its shape
To enable substrate to fit precisely to the active site
An enzyme substrate complex is formed
Enzyme stretched the existing bond to facilitate the reaction btw enzyme and substrate
Product is formed and released from active site
Enzyme changes back to its position


diagram from https://slideplayer.com/slide/5991600/

Lock and key mechanism

Active site of the enzyme represents the lock while substrate as the key
An enzyme is a large globular protein with specific 3D shape
The active site which is made up of specific arrangement of amino acids
The active site of the enzyme is the site for substrate to bind
The active site has a specific conformation that is complementary to the shape of substrate
Binding site of the enzyme forms an enzyme substrate complex
Activation energy and product are formed and released
At the end of the reaction the active site of the enzyme remain unchanged and the enzyme can be reused


diagram from https://www.123rf.com/photo_36876740_the-lock-and-key-mechanism-labeled-diagram.html



diagram from http://ibbiology.wikifoundry.com/page/Describe+the+induced-fit+model