Question

Long answer question.

Describe the models for enzyme actions.

Answer 1

There are two types of models:

• Lock and Key model:

1. The lock and Key model was first postulated in 1894 by Emil Fischer.
2. This model explains the specific action of an enzyme with a single substrate.
3. In this model, the lock is the enzyme and the key is the substrate.
4. The correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme).

Lock and key model

• Induced Fit model (Flexible Model):

1. Induced Fit model was first proposed in 1959 by Koshland.
2. This model states that the approach of a substrate induces a conformational change in the enzyme.
3. It is the more accepted model to understand the mode of action of an enzyme.
4. The induced-fit model shows that enzymes are rather flexible structures in which the active site continually reshapes by its interactions with the substrate until the time the substrate is completely bound to it.
5. It is also the point at which the final form and shape of the enzyme are determined.

Complex Flexible model