Enzymes -SUMMARY NOTE 1.
Structure of enzymes as globular proteins:
Enzymes are globular proteins which have a very specifically shaped active site.
This means that one enzyme will only catalyse one type of reaction.
They show great specificity.
The concepts of specificity and induced fit hypothesis:
Enzymes are very specific and will only bind to a particular substrate. Over the years a number of models have attempted to describe how an enzyme works. The lock and key model and the induced fit model are two examples of this.
The Lock and Key Model
1. The substrate molecule is drawn into the enzymes active site.
2. The active site does not change shape.
3. An enzyme-substrate complex is formed.
4. A reaction takes place and the enzyme-product complex is formed.
5. The products are released and the enzyme is free for use again.
However, this model fails to account for the flexibility found within enzymes.
The Induced Fit Model
1. A substrate molecule is drawn into the active site with a very similar shape.
2. The substrate induces a change upon the enzyme so that there is a perfect fit and an enzyme-substrate complex is formed.
3. The bonds in the substrate are strained and become weaker resulting in an enzyme-product complex.
4. The products are released and the enzymes returns to its original shape.
Enzymes are catalysts that reduce activation energy:
An enzyme is a biological catalyst. A catalyst is something that changes the rate of reaction without being used up and is reformed at the end of the...