BIOC 202 Lecture Notes - Lecture 10: Oxyanion Hole, Serine Protease, Tetrahedral Carbonyl Addition Compound
Document Summary
Examples of enzyme function: chymotrypsin serine protease in the small intestine. But peptide bonds are quite stable due to resonance (double bond characteristics) charged) and not as reactive as a regular c=o: this means you need a more powerful nucleophile. Chymotrypsin can cleave the peptide bond on the carboxy-terminal side of large hydrophobic amino acid residues such as phe, trp, tyr, met: only cuts the peptide bond on the c-terminal side (see slide) Chymotrypsin is composed of 3 chains formed by the cleavage of a single polypeptide: it does not have quaternary structure. Even though it is made up of multiple chains, it originally came from one peptide chain. Chymotrypsin has a highly reactive serine (s195) in the active site that can act as a strong nucleophile. Asp 102 can also h-bond with his 57, positioning his 57 and making it a better proton acceptor. Asp 102, his 57, and ser 195 are known as the catalytic triad.
