The Key and Lock Model , The Models of Enzyme Action

The Key and Lock model


This model was discovered by a scientist Emil Fischer in 1890.

Statement of lock & key model:

The lock and key model states that:
Only a specific enzyme can transform only a specific substrate into products.
According to this model, the active site is a rigid structure. Because of its rigidity, it cannot be altered during any step of the reaction. Later studies have not supported this model in all the reactions.

Lock and key model has some important features:

1. Enzymes acts as a lock:

In the lock and key model, enzymes look and work like lock-in chemical reactions. The body contains many enzymes and many substrates.  But correct/specific substrate can only unite with a specific enzyme.  Specific Enzyme can attract a specific substrate to accelerate a chemical reaction.

2. Active Sites:

Active sites are present on every enzyme. It allows specific substrates to attach for proceeding reaction further. Active sites work and look like a keyhole in a lock. It looks like a lock on a door. Thus only specific keys will wit on the key~holes. Finally, only a specific key can open a specific lock. In fact, the wrong key can't open the lock.

3. Substrates acts as keys:

Each enzyme will only respond to one or two keys/substrates. These substrate acts as a key for enzyme lock. Enzyme locates its specific substrate. Appropriate substrate attaches on the receptor site. Then the enzyme-substrate complex will be formed. So, after that chemical can occur.

4. Inhibitors:

Inhibitors jam the lock/enzyme active site. They work like the key. They attach to the key~holes ( Active site). But cannot open the lock. They completely STOP the chemical reaction or slows down.

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