Human cholinesterase exists in two forms--acetylcholinesterase located in tissue microsomes and red blood cells and serum cholinesterase found in serum or plasma. The two enzymes display marked differences in structure, substrate specificity, biological function, and origin. Contemporary methods employ acylthiocholine as substrate for serum cholinesterase and a second coupled reaction of thioch...

We describe an equilibrium assay for measuring release of plasminogen activator form blood-vessel walls and report data from 125 individuals free of overt thromboembolic disease. Excess human plasminogen is added to the euglobulin fraction of plasma obtained before and after venous occlusion at mean systolic pressure. To measure plasmin generation in these samples, we used the chromogenic plasm...

Ampicillin-resistant and -susceptible strains of Haemophilus influenzae were tested for susceptibility to 16 antibiotics. Chloramphenicol and a new cephalosporin, cefamandole, were most active with minimal inhibitory concentrations (MICs) for all bacteria tested between 0.5 to 2.0 mug/ml. All but two organisms were susceptible to tetracycline. Ampicillin-resistant strains of H. influenzae were ...

To obtain basic information on the detection of cellulolytic activity in Auricularia auricula-judae, the influences of dye reagent, pH, and temperature were assessed. Chromogenic dye (congo red, phenol red, remazol brilliant blue, and trypan blue) was individually incorporated into a medium containing either carboxymethyl-cellulose, Avicel, or D-cellobiose as a polysaccharide carbon substrate. ...

In contrast to earlier assays, the prothrombin determination described here uses a two-step reaction: first, prothrombin is activated with human factor Xa, phospholipids, Ca++ and factor V; second, the amount of activated prothrombin is assayed by the proteolysis of added fibrinogen. The assay is dependent only on prothrombin, and independent of other components of thrombin generation. Carboxy-...

The anthrax lethal factor (LF) is a Zn2+ endopeptidase specific for mitogen-activated protein kinase kinases (MAPKKs), which are cleaved within their N termini. Here, the proteolytic activity of LF has been investigated using novel chromogenic MAPKK-derived peptide substrates, which allowed us to determine the kinetic parameters of the reaction. LF displayed maximal proteolytic activity at the ...

This study presents detection of free polyethylene glycol (PEG) and conjugated PEG in western blot assay using anti-PEG rabbit monoclonals specific to methoxy group of PEG. In a chromogenic western blot assay, detection limit (DL) for free and PEGylated protein was 2.5 μg and 0.5 μg, respectively. Using chemiluminescence substrate, DL of PEGylated granulocyte colony stimulating factor (GCSF) wa...

We describe a new chromogenic substrate and assay for determining N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) activity in normal and pathological human urine. The novel substrate, ammonium 5-[4-(2-acetamido-2-deoxy-beta-D-glucopyranosyloxy)-3- methoxyphenylmethylene]-2-thioxothiazolidin-4-one-3-ethan oate (VRA-GlcNAc), is prepared by condensation of vanillyl N-acetyl-beta-D-glucosaminide...