Studies on Nature of So-Called Antiplasmin Measured By Chromogenic Substrate S-2251 and Its Automatic Determination With ABA 100

Using chromogenic substrate S-2251, authors studied on the nature of so-called antiplasmin and on the application of Coatest to automatic determination. As to several protease inhibitors, correlation performed vs single radial immunodiffusion yielded a regression of Y=19.5X-18.6 and r=0.91 for α2PI ;r=-0.15, 0.13, 0.46 0.28 for α2M, α2AT, AT-III and CIINA respectively. Purified protease inhibitors except α2PI did not exhibit immediate inhibition to human plasmin. The automation of chromogenic substrate method was studied with ABA Bichromatic Analyser Model 100 and auxiliary dispenser. 25 microliter of diluted plasma and 250 microliter of plasmin of known activity were added simultaneously to 100 microliter of substrate S-2251. Reaction rate was assayed with the use of two wavelengths, 450/415. Excellent correlation with manual protocol was observed, r=0.985 and Y=0.88X=8.7. Determination of within-day precision of automatic assay for three sample concentrations (Antiplasmin 25%, 100%, 150%) gave C.V. of 1.5%, 1.71% and 4.46% respectively. Thus, authors arrived at the conclusion that 1) α2PI is mainly determined as protesae inhibitor with the use of S-2251, 2) ABA 100 was successfully employed for automatic determination of antiplasmin with the use of simultaneous addition of plasma and plasmin to substrate solution.