In Experimental Tests of Enzyme Evolution,a Gene Encoding an Enzyme

Multiple Choice

In experimental tests of enzyme evolution,a gene encoding an enzyme was subjected to multiple cycles of random mutagenesis and selection for altered substrate specificity.The resulting enzyme with altered substrate specificity had multiple amino acid changes.Where in the enzyme might these amino acid changes be located?

A) only in or near the active site
B) only in the hydrophobic interior of the folded protein
C) only on surface sites distant from the active site
D) in or near the active site,in the hydrophobic interior,and/or at surface sites distant from the active site