Question

Describe the concept of enzyme-substrate binding affinity, and detail a situation where binding affinites could be applied in the regulation of the enzymatic activity.

Answer 1

Enzyme and substrate are complimentary to each other. Which means an enzyme molecule can bind to only a particular substrate molecule. There are active sites on the surface of the enzyme molecule, which are of specific shapes and specific amino acid groups. Those substrates which can bind to the groups and fit in to the active site can only have the enzymatic effect. An enzyme with low Km will have high affinity to the substrate and hence will have higher rate of reaction.

An allosteric modulator can be used to change the shape of the active site. When active site is changed, the affinity of the enzyme reduces to the substrate. Enzyme substrate activity occurs only at higher concentration of the substrate. This is how the enzyme activity can be regulated by changing the enzyme affinity to substrate.

An allosteric modulator is a molecule which binds to a different site called allosteric site and changes the shape of the enzyme.