Question

Tryptophan synthetase of E. coli, a typical bifunctional oligomeric enzyme consists of
A. a protein A and one subunit A
B. a protein designated A
C. two proteins designated A and B
D. a protein designated B

Answer 1

Hint:
Tryptophan is an essential amino acid that is needed for the body to make serotonin. This molecule is made up of a single protein chain, but it can only be created by two different proteins - one called A, and the other called B. Tryptophan synthetase is a typical bifunctional enzyme that consists of both proteins. This enzyme helps to make tryptophan, and it is found in many different types of bacteria, including E. coli.

Complete step by step answer:
Tryptophan synthetase of E. coli is a typical bifunctional oligomeric enzyme consisting of two proteins designated A and B.
The role of protein A in enzymatic activity has been extensively studied, while its role in catalysis is less clear.
Protein B has been shown to be responsible for hydrogen bonding between Trp-185 and Tyr-182, which leads to the transfer of electrons from NADH via the pyridine nucleotide quinone (PNQ) ring system to water molecules during catalysis.

Option ‘C’ is correct

Note:
This enzyme is used in the biosynthesis of many essential amino acids. It catalyzes the formation of tryptophan from ammonia and acetyl-CoA. This reaction is catalyzed by A and B proteins, respectively. While both proteins work independently, they can also be activated simultaneously to increase enzyme activity. The importance of this enzyme lies in its abundance as well as its crucial role in protein synthesis for many important metabolites like vitamin B2, vitamin K2, and tryptophan.