A new chromogenic substrate that is blocked at the nonreducing end, 4,6-benzylidene-a-D-4-nitrophenylmaltoheptaoside, is used to determine a-amylase (EC 3.2.1.1) activity in serum in a coupled assay with a-glucosidase (EC 3.2.1.20) and glucoamylase (EC 3.2.1.3) as auxiliary enzymes. The duration of the lag phase between 25 and 37#{176}C is <90 s, and the molar absorptivity of 4-nitrophenol is c...

Cholera outbreak is more common in developing countries. The causative agent of the disease is Vibrio cholerae strains O1 and O139. Traditional diagnostic testing for Vibrio is not always reliable, because Vibrio can enter a viable but non cultivable state. Therefore, nucleic acid-based tests have emerged as a useful alternative to traditional enrichment testing.       In this investigation, a...

A medium containing a chromogenic substrate was developed for the enumeration of Escherichia coli on the basis of beta-glucuronidase activity. In this medium there was an inverse linear relationship between the log initial E. coli concentration and the time taken for the color to reach a threshold optical density of 0.05. This relationship applied even when the E. coli population contained 5% b...

It has been shown that the insertion of antigenic peptides of the foot-and-mouse disease virus (FMDV) into specific sites of the bacterial enzyme β-galactosidase causes a severe reduction of the activity of this enzyme which can be recovered upon antibody binding to the inserted antigenic peptide [1]. In principle, the recovery of β-galactosidase activity upon antigen-antibody binding allows th...

Three methods (membrane filtration, multiple tube fermentation, and chromogenic substrate technology kits manufactured by IDEXX Laboratories, Inc.) are routinely used to measure indicator bacteria for beach water quality. To assess comparability of these methods, quantify within-laboratory variability for each method, and place that variability into context of variability among laboratories usi...

Enterotoxigenic Escherichia coli (ETEC) is the causative agent of a wide range diseases, which are important cause illness and mortality in piglets. ETEC strains expressing F4 fimbriae frequently associated with post-weaning diarrhea (PWD) lead to great economic losses swine production industry worldwide. The aim this study was establish rapid effective isothermal amplification method for detec...

Some factors affecting the use of chromogenic substrates with Limulus lysate for assaying bacterial endotoxins in blood have been assessed. It was found that endogenous amidases, which degrade the substrate, could be inactivated by heating serum at 60 degrees C for 15 min. Endotoxin was found not to be removed from serum during clotting. A potent inhibitor of the activated lysate was found to b...

Immunodetection techniques are dependent on enzyme-protein conjugates for the visualisation of antigen-antibody complexes. One of the most widely used is the avidin-biotin-peroxidase complex (ABC) method. The present study demonstrates that direct treatment of goldfish and salamander retinal sections with ABC, followed by an incubation with the chromogenic substrate 3,3-diaminobenzidine tetrahy...

A simple dot blot immunoenzymatic assay system was developed using polyester cloth coated with an oligo-DNA aptamer to provide a high-affinity macroporous surface for the efficient capture of a model protein analyte (thrombin) in complex sample matrices such as foods. Bound thrombin was detected immunoenzymatically using a peroxidase-linked antithrombin antibody and a chromogenic substrate. A u...

The two major isozymes of N-acetylhexosaminidase, namely hexosaminidases A and B were quantitatively determined in tissues and biological fluids of both normal individuals and Tay-Sachs patients. The determination was carried out by two sensitive immunoassays:radial immunodiffusion, using chromogenic substrate, and radioimmunoassay, which were developed in this study. For this purpose [correcte...