Angiotensin-converting enzyme-like activity in crab gills and its putative role in degradation of crustacean hyperglycemic hormone.
Angiotensin-converting enzyme-like enzyme activity (ACELA) was found in Carcinus maenas using reverse phase high performance liquid chromatography (RP-HPLC) analysis of degradation kinetics of a synthetic substrate (Hippuryl-histidyl-leucine) and a specific inhibitor (captopril). Gills contained the highest ACELA, then brain, muscle, and testis, respectively, while no activity was detected in the following tissues: hepatopancreas, hindgut, hypodermis, heart, and hemolymph. ACELA present in gill membranes exhibited a K(m) of 0.23 mM and V(max) of 7.6 nmol with synthetic substrate. The enzyme activity was dependent on Cl- concentration and was markedly inhibited by captopril, lisinopril, and EDTA. Addition of Zn2+ to membranes previously treated with EDTA restored 89% activity, suggesting that C. maenas ACELA is a Zn2+ metalloenzyme. Gill membranes prepared from premolt crabs showed similar levels of ACELA to those of the intermolt animals. Administration of captopril in vivo lengthened the half life of circulating CHH, while in vitro incubation of gill membranes with captopril reduced CHH. These results suggest that C. maenas ACELA present in gills is likely to be involved in degradation of this neuropeptide.
Chung
J Sook
JS
Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA. chung@comb.umbi.umd.edu
Webster
S G
SG
D000596:Amino Acids / Q000378:metabolism; D000803:Angiotensin I / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D060829:Arthropod Proteins; D003386:Brachyura / Q000201:enzymology* / Q000378:metabolism; D002216:Captopril / Q000494:pharmacology; D002413:Cations, Divalent; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004492:Edetic Acid / Q000494:pharmacology; D005880:Gills / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D006207:Half-Life; D007447:Invertebrate Hormones; D007457:Iodine Radioisotopes; D007700:Kinetics; D017706:Lisinopril / Q000494:pharmacology; D008297:Male; D008670:Metals / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000493:pharmacokinetics; D009842:Oligopeptides / Q000378:metabolism; D007703:Peptidyl-Dipeptidase A / Q000302:isolation & purification / Q000378:metabolism*; D014018:Tissue Distribution
D000596:Amino Acids; D000806:Angiotensin-Converting Enzyme Inhibitors; D060829:Arthropod Proteins; D002413:Cations, Divalent; D007447:Invertebrate Hormones; D007457:Iodine Radioisotopes; D008670:Metals; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; C015947:hyperglycemic hormone, crustacean; C010980:hippuryl-histidyl-leucine; D000803:Angiotensin I; D004492:Edetic Acid; D002216:Captopril; D017706:Lisinopril; D007703:Peptidyl-Dipeptidase A