title: Presence of angiotensin converting enzyme isoforms in larval lepidoptera (Spodoptera littoralis).
abstract: In this research the presence of angiotensin converting enzyme (ACE) in larvae of the lepidopteran Spodoptera littoralis was evaluated. Making use of the substrate Abz-FRK-(Dnp)P-OH and the specific inhibitor captopril at 10 microM, ACE activity was determined in a fluorescence assay for intact larvae, hemolymph, head, midgut and dorsal tissue. In dorsal tissue and hemolymph, ACE activity was highest. These data are consistent with a possible role for ACE in contractions of the dorsal vessel and metabolism of circulating peptide hormones in the hemolymph. After the presence of ACE was confirmed, a sequential procedure of anion exchange and size exclusion chromatography was applied to purify ACE from whole wandering larvae (last stage). With this procedure, three different ACE pools were collected that cleaved the fluorogenic substrate Abz-FRK-(Dnp)P-OH. Activity could be inhibited by a final concentration of 2.5 microM captopril. In addition, two out of three samples eluted at different salt concentration and thus ACE 1, 2 and 3 represent at least two different ACE isoforms. These data reveal that ACE is present in S. littoralis and that at least two out of three isolated ACE forms are truly isoforms.
authors.affiliation: Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium. els.lemeire@ugent.be
authors.forename: E
authors.initials: E
authors.lastname: Lemeire
authors.forename: J
authors.initials: J
authors.lastname: Van Camp
authors.forename: G
authors.initials: G
authors.lastname: Smagghe
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D002216:Captopril / Q000494:pharmacology; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism; D007814:Larva / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D007703:Peptidyl-Dipeptidase A / Q000302:isolation & purification / Q000378:metabolism*; D018411:Spodoptera / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D007527:Isoenzymes; D002216:Captopril; D007703:Peptidyl-Dipeptidase A