CMB 311 Lecture Notes - Lecture 7: Serine Protease, Enzyme Catalysis, Pancreatic Ribonuclease

• School: URI
• Department: Cell and Molecular Biology
• Course: CMB 311
• Professor: Steven Gregory

Document Summary

Asp, glu, his, cys, arg, lys have ionizable r groups whose pka values can be perturbed by the local environment. Neutral ph, protons coming off his easily. His 12 acts as a general base to remove a proton. His 119 functions as a general acid to protonate. Know which is acid which is base. Serine protease that hydrolyses proteins using an active site serine residue. Critical active site residues are ser195, his57, asp102, His acts as both acid and base. Uses both acid-base catalysis and covalent catalysis. Both enzymes have a histidine acting as a base to remove a proton from an -oh group. Rnase a his12 removes a proton from a substrate -oh. Chymotrypsin his57 removes a proton from an enzyme serine -oh. Note that the attacking oxygen is different in the two enzymes: the substrate -o of rna in the rnase a reaction, and enzyme ser -o of the chymotrypsin.