A rapid and specific method for the determination of oxytocinase (cystine aminopeptidase) activity using continuous flow analysis and S-benzyl-L-cysteine-p-nitroanilide as substrate.
1. An automated method is described for the assay of pregnancy serum cystine aminopeptidase (Oxytocinase, E.C. 3.4.1.10) using continuous flow analysis. S-Genzyl-L-cysteine-p-nitroanilide, the most highly specific substrate so far available for oxytocinase is employed in this assay. Comparison with the manual method from which it has been developed, gave a correlation coefficient of 0.98. Reaction of oxytocinase on the substrate liberated p-nitroaniline, the absorption of which is measured at 410nm. 2. Blank values are eliminated by the incorporation of a dialyzer in the manifold design and thereby effectively increasing the rate of assay sample to 40 per hour. The lag phase (a) of the continuous flow analysis is 0.17 min while the exponential phase (b) is 0.31 min. Using a 2:1 sample to wash ration the carry-over is 3% at a 95% of steady states.
D000626:Aminopeptidases / Q000097:blood*; D000813:Anilides; D001322:Autoanalysis / Q000379:methods; D001593:Benzyl Compounds; D003545:Cysteine; D010122:Cystinyl Aminopeptidase / Q000097:blood*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007202:Indicators and Reagents; D009574:Nitro Compounds; D011247:Pregnancy; D013997:Time Factors
D000813:Anilides; D001593:Benzyl Compounds; D007202:Indicators and Reagents; D009574:Nitro Compounds; D000626:Aminopeptidases; D010122:Cystinyl Aminopeptidase; D003545:Cysteine