p-Nitrophenyl acetate is the most commonly used substrate for detecting the catalytic activity of esterases, including those that activate prodrugs in human cells. This substrate is unstable in aqueous solution, limiting its utility. Here, a stable chromogenic substrate for esterases is produced by the structural isolation of an acetyl ester and p-nitroaniline group using a trimethyl lock moiet...

A rapid assay for serum amylase activity has been developed based on the use of a new chromogenic substrate-Cibachron Blue-amylose. The procedure requires 0.1 ml of serum and measures the production of soluble chro. mogen, the formation of which islinearwith enzyme activity. Normal human serum has a mean amylase activity of 118 ± 37 (SD) mg dye/100 ml/15 mm or, in international units, 78 ± 24 (...

Prothrombin is determined with the aid of a recently developed assay, based on the amidolysis of a chromogenic substrate. The assay proved to be reliable when it was compared with more conventional coagulation assays in the control of oral anticoagulant therapy, both in the therapeutic range and in a case of overdosage. As is the case in coagulation tests, heparin therapy remains a disturbing c...

BBL CHROMagar VanRE (CVRE) was compared with bile esculin azide agar plus vancomycin to screen for vancomycin-resistant enterococcus (VRE) colonization. CVRE distinguishes Enterococcus faecalis (green colonies) from Enterococcus faecium (mauve colonies) on the basis of chromogenic substrate use. CVRE sensitivity and specificity were 98.6% and 99.1%. Positive and negative predictive values were ...

Phosphorothioate oligonucleotides (PS ODNs) prolong the activated partial thromboplastin time in human plasma by inhibition of intrinsic tenase (factor IXa-factor VIIIa) activity. This inhibition was characterized using ISIS 2302, a 20-mer antisense PS ODN. ISIS 2302 demonstrated hyperbolic, mixed-type inhibition of factor X activation by the intrinsic tenase complex. The decrease in V(max(app)...

Haemophilia A severity is closely correlated to the factor VIII (FVIII) activity, which can be measured in different ways. The original one-stage clotting assay is still the most widely used. The two-stage coagulation assay eliminated many of the drawbacks of the one-stage assay and was further developed into the chromogenic assay, a two-staged test with purified coagulation factors in the firs...

Phosphatase (APase) enzymes including phytases have broad applications in diagnostic kits, poultryfeeds, biofertilizers and plant nutrition. Because of high levels of sequence diversity among phosphatases,an efficient functional screening method is a crucial requirement for the isolation of the encodinggenes. This study reports a functional cloning screening method for the iso...

The effects of 50 antibiotics on the detection and determination of bacterial endotoxins by the chromogenic method using a Limulus reagent (Tachypleus hemocyte lysate) and a chromogenic substrate of p-nitroaniline derivatives were tested, and the antibiotic concentration for 50% inhibition of the chromogenic reaction in the presence of 0.5 ng of endotoxin (Escherichia coli 0111:B4) per ml was e...