Question

how many HIS 3 and URA 3 enzymes are needed when we add 10 mM 3-amino-1,2,4-triazole (3 AT) to the growth medium as a competitive inhibitor of HIS3?

Answer 1

Answer: In competitive inhibition an inhibitor molecule mimics like an enzyme molecule that competes with enzyme (also referred to as substrate sometimes) for an active site and prevents the binding of enzyme to its active site. In most cases, an inhibitor is an analog of the enzyme.

According to the question, HIS3 and URA3 are enzymes involved which catalyzes the reaction of gene products of HIS3 gene and URA3 gene for the growth of yeast. These enzymes are added to the yeast growth media. However, along with this, 10mM of 3AT is also added which is a competitive inhibitor of HIS3.

In a general way, a competitive inhibition can be overcome by increasing the concentration of the enzyme (or substrate). So, in a similar way, concentration HIS3 must be slightly higher than the 10mM so that it combats the inhibitory effect of 3AT. By doing so, substrate molecules will displace the inhibitor molecules and make their way for the active site.