Use of MagniSep chromium dioxide particles in an immunoassay system.

The use of chromium dioxide particles as a solid support for very sensitive and rapid immunoassays, is the result of the combination of large surface area (40 m2) and high protein uptake capacity (40 mg/g) allowing rapid capture kinetics and high binding capacity. Magnetic and physical properties of these particles give a rapid separation, a complete resuspension and a rapid high-efficiency washing, highly desirable characteristics for efficient automation of immunoassays. Good precision and accuracy, exemplified by excellent recovery, parallelism and correlation were demonstrated.

Development and performance of a fully automated method for assay of C-reactive protein in the aca discrete clinical analyzer.

A quantitative immunoassay for C-reactive protein (CRP) has been developed for use in the Du Pont aca discrete clinical analyzer. Particle-enhanced turbidimetric immunoassay (PE-TIA) technology is used. The method has a CV of less than 10% in the range 2 to 120 mg/L.

A quantitative automated immunoassay for fibrinogen/fibrin degradation products.

We describe a prototype quantitative automated assay for fibrin and fibrinogen degradation products, a particle-enhanced turbidimetric inhibition immunoassay (PETINIA) in the Du Pont aca discrete clinical analyzer. This assay involves a latex particle reagent with covalently bound fibrinogen and a polyclonal antiserum raised in rabbits against human fibrinogen. A special secondary sample-collection tube quantitatively removes fibrinogen from citrated plasma and inhibits further fibrinolysis, independent of heparin concentration.

Reaction of azapeptides with human leukocyte elastase and porcine pancreatic elastase. New inhibitors and active site titrants.

The reaction of a series of azapeptides with porcine pancreatic (PP) elastase and human leukocyte (HL) elastase has been studied and a series of new inhibitors and active site titrants were found for both PP elastase and HL elastase. Azapeptide p-nitrophenyl esters acylate both HL and PP elastase to form stable acylenzymes, which can be used for crystallographic studies. We have investigated the effect of a P1, P2, or P3 aza-amino acid residue on the reactivity of azapeptides with elastase.

Reaction of azapeptides with chymotrypsin-like enzymes. New inhibitors and active site titrants for chymotrypsin A alpha, subtilisin BPN', subtilisin Carlsberg, and human leukocyte cathepsin G.

A series of new azapeptide p-nitrophenyl esters containing a variety of P1 aza-amino acid residues have been synthesized, and the reaction of these azapeptides with chymotrypsin A alpha, subtilisin BPN', subtilisin Carlsberg, and human leukocyte cathepsin G at pH 4-7 has been studied. These azapeptides were found to be very useful as active site titrants and inhibitors of serine proteases with chymotrypsin-like specificity. Stable acyl derivatives of serine proteases are formed in the reaction with azapeptides and can be used for future crystallographic investigations.