title: Distribution and characterization of angiotensin-converting enzyme-like activity in tissues of the blue crab Callinectes sapidus.
abstract: Angiotensin-converting enzyme-like activity (ACELA) was determined in tissue homogenates of the blue crab, Callinectes sapidus, using the synthetic substrate hippuryl-histidyl-leucine (Hip-His-Leu) and the specific inhibitor, captopril. ACELA was highest in gill homogenates followed by the hepatopancreas and hemolymph with specific activities of 1.69, 0.37 and 0.10 nmol/min/mg protein, respectively. Gill enzyme activity was membrane-associated and no difference in activity was noted between anterior and posterior gills. The enzyme preparation from gill membranes was activated by chloride and had a Km of 4.1 +/- 0.4 mmol and a Vmax of 39.5 +/- 2.0 nmol/min/mg protein. The enzyme was strongly inhibited by captopril and lisinopril with IC50 s of 3.8 x 10(-8) and 2.6 x 10(-8) M. The enzyme was less strongly inhibited by angiotensin II and SQ-20881 with IC50 s of 5.1 x 10(-5) and 2.5 x 10(-6) M, respectively.
authors.affiliation: Department of Biology, College of Charleston, SC 29424.
authors.forename: J W
authors.initials: JW
authors.lastname: Smiley
authors.forename: M T
authors.initials: MT
authors.lastname: Doig
mesh_terms: D000595:Amino Acid Sequence; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D003386:Brachyura / Q000378:metabolism*; D005880:Gills / Q000201:enzymology; D006458:Hemolymph / Q000187:drug effects / Q000201:enzymology; D006868:Hydrolysis; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D012965:Sodium Chloride; D007703:Peptidyl-Dipeptidase A