In vitro degradation of the C-terminal octapeptide of cholecystokinin by 'enkephalinase A'.
As the C-terminal octapeptide of cholecystokinin represents a putative neurotransmitter in the central nervous system, the membrane-bound enzymes involved in its inactivation were investigated. Two aminopeptidases, involved in the cleavage of enkephalins, and a metalloendopeptidase were identified in extracts of solubilized synaptic membranes. The metalloendopeptidase, which cleaves CCK-8 at the Trp30-Met31 bond, appeared to be indistinguishable from 'enkephalinase A1' on the basis of its chromatographic behaviour, sensitivity to inhibitors and relative affinities for Met- and Leu-enkephalins. This finding indicates that CCK-8 is inactivated in vitro by the same peptidases as enkephalins.
D000818:Animals; D002766:Cholecystokinin / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D007700:Kinetics; D015260:Neprilysin; D018377:Neurotransmitter Agents / Q000096:biosynthesis; D010446:Peptide Fragments / Q000378:metabolism*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D051381:Rats; D012844:Sincalide; D013379:Substrate Specificity
D018377:Neurotransmitter Agents; D010446:Peptide Fragments; D002766:Cholecystokinin; D010450:Endopeptidases; D007703:Peptidyl-Dipeptidase A; D015260:Neprilysin; D012844:Sincalide