A gene codes for an enzyme that has 3 main domains; a substrate-binding catalyti
ID: 52510 • Letter: A
Question
A gene codes for an enzyme that has 3 main domains; a substrate-binding catalytic site, an ATP hydrolysis site that powers the conversion of substrate, and an allosteric inhibitor binding site. The mRNA for this enzyme has 2 different splice isoforms, one with all 3 domains and one that lacks the ATP hydrolysis site. You have limited substrate and 1000 units of the 3 domain enzyme and measure the reaction rate. What do you think would happen to the reaction rate if you had added 1000 units of the 2 domain isoform along with the 1000 units of the 3 domain isoform to a limited amount of substrate?
Explanation / Answer
The reaction rate become lower on the addition of 1000 units of the 2 domain isoform because the substrate is limited and the 2 domain isoform of the enzyme will block some of the substrate and will not convert them in to the product.
The reason behind not to convert them is that the 2 domain isoform lacks the ATP hydrolysis site so that could not provide the sufficient energy to the substrate that can convert to the product.