A recent discovery has suggested that a gene mutation results in several amino acid substitutions within an active site.The following substitutions have been identified and are each expected to form the active site:

It was also noticed that a coenzyme molecule containing a hydroxyl (-OH)group binds to the mutated protein in approximately the same location as the original serine but does not alter the structure of the protein in anyway.Based on your knowledge of amino acids,enzymes,and catalysis,which of the following is a REASONABLE conclusion?
A)The mutant protein cleaves on the carboxy side of phenylalanine.
B)The mutant protein cleaves peptide bonds on the carboxy side of glutamate or aspartate.
C)The mutant protein cleaves peptide bonds on the carboxy side of lysine or arginine.
D)The mutant protein functions identical to chymotrypsin.
E)The mutant protein has no function.

Question

A recent discovery has suggested that a gene mutation results in several amino acid substitutions within an active site.The following substitutions have been identified and are each expected to form the active site:

It was also noticed that a coenzyme molecule containing a hydroxyl (-OH)group binds to the mutated protein in approximately the same location as the original serine but does not alter the structure of the protein in anyway.Based on your knowledge of amino acids,enzymes,and catalysis,which of the following is a REASONABLE conclusion?
A)The mutant protein cleaves on the carboxy side of phenylalanine. 
B)The mutant protein cleaves peptide bonds on the carboxy side of glutamate or aspartate. 
C)The mutant protein cleaves peptide bonds on the carboxy side of lysine or arginine. 
D)The mutant protein functions identical to chymotrypsin. 
E)The mutant protein has no function.

Quizplus · Accepted Answer

The fact that the coenzyme binds to the mutated protein in the same location as the original serine suggests that the coenzyme is acting as a substitute for the missing serine residue. Serine is a key amino acid in catalyzing cleavage of peptide bonds on the carboxy side of glutamate or aspartate residues, so it is reasonable to assume that the mutant protein will also cleave peptide bonds on the carboxy side of these residues. Therefore, choice B is the most reasonable conclusion.

A Recent Discovery Has Suggested That a Gene Mutation Results