Simple, refined fluorometric method for measuring cystyl-amino peptidase activity.
Cystyl-amino peptidase (EC 3.4.11.3) activity in serum or plasma was measured fluorometrically using L-cystine-di-beta-naphthylamide in the absence and presence of thiol such as mercaptoethanol. In the presence of thiol, L-cystine-di-beta-naphthylamide is converted to L-cysteine-beta-naphthylamide, and the enzyme activity to hydrolyze L-cysteine-beta-naphthylamide can be measured, while in the absence of thiol, the enzyme activity to hydrolyze L-cystine-di-beta-naphthylamide is determined. Thiol added did not affect various aminopeptidase activities. The present method is able to measure the enzyme activity hydrolyzing L-cystine-di-beta-naphthylamide and L-cysteine-beta-naphthylamide simultaneously and separately using only L-cysteine-di-beta-naphthylamide. This method is simple, sensitive and useful in clinical routine work, assessing placental function for the evaluation of the pregnant status.
D000577:Amides / Q000378:metabolism; D000626:Aminopeptidases / Q000097:blood*; D003553:Cystine / Q000031:analogs & derivatives / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008623:Mercaptoethanol / Q000494:pharmacology; D011247:Pregnancy; D013050:Spectrometry, Fluorescence
D000577:Amides; C015769:cystine-di-beta-naphthylamide; D003553:Cystine; D008623:Mercaptoethanol; D000626:Aminopeptidases