peptidase activity Catalysis of the hydrolysis of a peptide bond. A peptide bond is a covalent bond formed when the carbon atom from the carboxyl group of one amino acid shares electrons with the nitrogen atom from the amino group of a second amino acid. EC:3.4 GO:0008233 Reactome:REACT_106748 Reactome:REACT_110349 Reactome:REACT_13710 Reactome:REACT_19284 Reactome:REACT_93020 Reactome:REACT_99630 hydrolase, acting on peptide bonds molecular_function peptide hydrolase activity protease activity proteinase activity