Open AccessIdentification and Localization of a Synaptosomal Membrane Prolyl Endopeptidase from Bovine Brain
Author(s) -
O'Leary Rhona M.,
O'Connor Brendan
Publication year - 1995
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1995.tb20385.x
Subject(s) - prolyl endopeptidase , neprilysin , endopeptidase , neurotensin , chemistry , biochemistry , cytosol , neuropeptide , membrane , protease , enzyme , receptor
Prolyl endopeptidase, which has long been recognised for its importance in the degradation of several neuropeptides such as thyroliberin, luteinising hormone releasing hormone, angiotensin, substance P and neurotensin, has been widely characterised as a cytosolic enzyme. However, in this paper, we report the presence of a prolyl endopeptidase activity in the particulate fractions of bovine brain, which is distinct from that in the cytoplasm. This previously uncharacterised activity was found to reside in the synaptosomal membranes, a location which is highly significant for the inactivation of neuropeptides in brain. Following vigorous salt washing and osmotic shock, the prolyl endopeptidase activity was released from the membranes by treatment with the detergent Triton X‐100, and was partially purified by gel filtration on a Sephacryl S‐200HR column. This prolyl endopeptidase activity was shown to have a molecular mass (87 kDa) higher than the cytosolic prolyl endopeptidase but, from initial investigation, appears to demonstrate a similarly broad substrate specificity towards proline‐containing neuropeptides. The partially purified enzyme was inhibited by certain thiol‐protease inhibitors and was also found to be sensitive to the metal chelator 1,10‐phenanthroline.