Histidine residues are found in the active sites of numerous enzymes, including:
1. Serine Proteases: These enzymes, such as trypsin and chymotrypsin, use a histidine residue in their catalytic triad to facilitate the cleavage of peptide bonds. 2. Carbonic Anhydrase: Histidine residues in carbonic anhydrase help in the conversion of carbon dioxide to bicarbonate, playing a crucial role in pH regulation. 3. Metalloenzymes: Histidine often coordinates metal ions in metalloenzymes, assisting in redox reactions and substrate binding.
