An evaluation of the role of a pyroglutamyI peptidase, a post‐proline cleaving enzyme and a post‐proline dipeptidyI amino peptidase, each purified from the soluble fraction of guinea‐pig brain, in the degradation of thyroliberin in vitro

摘要: The degradation of thyroliberin (less than Glu-His-Pro-NH2) to its component amino acids by the soluble fraction guinea pig brain is catalysed four enzymes namely a pyroglutamate aminopeptidase, post-proline cleaving enzyme, dipeptidyl aminopeptidase and proline dipeptidase. 1. was purified over 90% homogeneity with purification factor 2868-fold yield 5.7%. In addition catalysing hydrolysis thyroliberin, acid pyroglutamate-7-amido-4-methylcoumarin peptide bond adjacent pyroglutamic residue in luliberin, neurotensin bombesin, bradykinin-potentiating B, anorexogenic dipeptides pyroglutamyl alanine valine. Pyroglutamyl eledoisin were not hydrolysed. 2. enzyme apparent electrophoretic 2298-fold 10.6%. N-benzyloxycarbonyl-glycylproline-7-amido-4-methylcoumarin. It did catalyse glycylproline-7-amido-4-methylcoumarin or His-Pro-NH2. 3. partially 301-fold 8.9%. His-Pro-NH2 but exhibit any endopeptidase activity against 4. Studies various functional reagents indicated that could be specifically inhibited 2-iodoacetamide (100% inhibition at an inhibitor concentration 5 microM), bacitracin (IC50 = 42 microM) puromycin 46 microM). Because their specific inhibitory effects these three key elements elucidation overall pathway for metabolism tissue enzymes.