Question

Which of these is not an example for stereo specificity?

(a) L-lactate dehydrogenase will act only on L-lactic acid, and not D-lactic acid

(b) D-glucose oxidase acting only on D-glucose and not L-glucose

(c) L-amino oxidase acts only on L-amino acids and not D-aminoacids

(d) Hexokinase phosphorylating one or more kind of hexoses

The question was posed to me in an interview for internship.

Question is from Specificity of Enzyme Action in chapter Enzymes of Enzyme Technology

Answer 1

Correct choice is (d) Hexokinase phosphorylating one or more kind of hexoses

Explanation: Hexokinase phosphorylating one or more kinds of hexoses is an example for broad substrate specificity and not stereo specificity. Stereo specificity is referred to as enzymes showing specificity towards only one type of isomers. Hence the examples for stereo specificity are as follows:

• L-lactate dehydrogenase will act only on L-lactic acid, and not D-lactic acid.

• D-glucose oxidase acting only on D-glucose and not L-glucose.

• L-amino oxidase acts only on L-amino acids and not D-aminoacids.