Purification and characterization of the Manduca sexta neuropeptide processing enzyme carboxypeptidase E.
The neuropeptide processing enzyme carboxypeptidase E (CPE) (E.C.3.4.17.10) has been well studied in vertebrates but its presence in invertebrates has not yet been reported. CPE activity in insects is present in membrane-bound and soluble forms. The soluble CPE has been purified to homogeneity from the brain of the tobacco hornworm Manduca sexta. It is a 57 kDa glycoprotein containing 9% sugars. It is activated 9.2 +/- 1.8 fold by CoCl2 and inhibited by chelating agents. Its sensitivity to guanidinoethyl-mercaptosuccinic acid, and its molecular mass, make this enzyme a good candidate to be the insect equivalent of the mammalian CPE. Furthermore, its lack of sensitivity towards p-(chloromercuri)benzenesulfonate puts it closer to the vertebrate carboxypeptidase M (CPM). We postulate that insects may possess a single protein fulfilling both CPE and CPM functions.
Stone
T E
TE
Sandoz Agro, Inc., Research Division, Palo Alto, California 94304-1104.
Li
J P
JP
Bernasconi
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000201:enzymology; D043423:Carboxypeptidase H; D002268:Carboxypeptidases / Q000302:isolation & purification* / Q000378:metabolism*; D002846:Chromatography, Affinity / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D018402:Manduca / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009479:Neuropeptides / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity
D006023:Glycoproteins; D009479:Neuropeptides; D011480:Protease Inhibitors; D002268:Carboxypeptidases; D043423:Carboxypeptidase H