peptidase activity serine-type peptidase activity Reactome:R-HSA-3132753 Reactome:R-HSA-9839072 Reactome:R-HSA-9839110 serine protease activity GO:0008236 Reactome:R-HSA-6801766 Reactome:R-HSA-1461993 Reactome:R-HSA-2022383 Catalysis of the hydrolysis of peptide bonds in a polypeptide chain by a catalytic mechanism that involves a catalytic triad consisting of a serine nucleophile that is activated by a proton relay involving an acidic residue (e.g. aspartate or glutamate) and a basic residue (usually histidine). molecular_function serine hydrolase activity