If serine 195 in chymotrypsin is mutated to tyrosine, it would typically result in a change in the protein's structure and potentially affect its function. Serine 195 is an important amino acid residue in chymotrypsin that participates in the catalytic activity of the enzyme. It acts as a nucleophile during the hydrolysis of peptide bonds.
When serine is replaced by tyrosine, which is a larger and more hydrophobic amino acid, it can disrupt the active site of chymotrypsin. This substitution may affect the enzyme's ability to bind and cleave peptide bonds efficiently. The mutation could potentially impair the enzymatic activity of chymotrypsin, leading to a change in its substrate specificity or catalytic efficiency.