What type of residues does chymotrypsin cleave at the C-terminal end?

Chymotrypsin is a serine protease that preferentially cleaves peptide bonds at the C-terminal end of aromatic amino acids. The specific residues that chymotrypsin targets are phenylalanine (Phe), tryptophan (Trp), and tyrosine (Tyr). This specificity is due to the enzyme's S1 pocket, which is hydrophobic and accommodates the aromatic side chains of these amino acids, facilitating the cleavage of peptide bonds adjacent to them.

The cleavage occurs after these residues because the enzyme's active site is structured to recognize the bulky, hydrophobic characteristics of the side chains of these amino acids. This preferential cleavage is a key feature of chymotrypsin's enzymatic function, distinguishing it from other proteases that might target different residues.

Understanding this specificity is essential in biochemistry, particularly in protein digestion and the general function of proteolytic enzymes in various biological processes.