Considering the active site of serine protease enzymes, a fair generalization is that:
A) Nearly all of the amino acid R-groups of the protein must directly participate in catalysis.
B) All of the amino acid residues which are involved in the active site are adjacent because they are located on the same short stretch of the polypeptide chain.
C) The conformation of the active site region does not exist at all until the substrate is bound to the enzyme.
D) The amino acid residues which form the active site are in close proximity because of the specific three-dimensional shape the protein adopts in its native state.
E) Only one amino acid residue is involved in the active site.

Question

Quizplus · Accepted Answer

The active site of serine protease enzymes is a region on the protein that binds to the substrate and carries out the chemical reaction. This requires specific three-dimensional shape of the protein, which brings the amino acid residues involved in the active site into close proximity. While some amino acids may play a more direct role in catalysis than others, nearly all the residues in the active site play some role in substrate recognition or catalysis. The conformation of the active site region exists in the native state of the enzyme, but it may change slightly upon substrate binding. Therefore, the best generalization is that the amino acid residues which form the active site are in close proximity because of the specific three-dimensional shape the protein adopts in its native state.

Considering the Active Site of Serine Protease Enzymes, a Fair