Enzymic marker

Female NMRI mice were exposed to 100 ppm of hydrogen sulfide for 2 hours at 4-day intervals excitement was observed (Savolainen et al. 1980). Exposure also resulted in decreased cerebral ribonucleic acid (RNA), decreased orotic acid incorporation into the RNA fraction, and inhibition of cytochrome oxidase. An increase in the glial enzyme marker, 2, 3 -cyclic nucleotide-3 -phosphohydrolase, was seen. Neurochemical effects have been reported in other studies. Decreased leucine uptake and acid proteinase activity in the brain were observed in mice exposed to 100 ppm hydrogen sulfide for 2 hours (Elovaara et al. 1978). Inhibition of brain cytochrome oxidase and a decrease in orotic acid uptake were observed in mice exposed to 100 ppm hydrogen sulfide for up to 4 days (Savolainen et al. 1980). 

R.E. Ionescu, C. Gondran, S. Cosnier, L.A. Gheber, and R.S. Marks, Comparison between the performances of amperometric immunosensors for cholera antitoxin based on three enzyme markers. Talanta... 

When using HRP as an enzyme marker, incubate the sections for 15 min in 0.3% H2O2 in either methanol or water to quench endogenous peroxidase (see Sect. 5.2). If endogenous peroxidase activity does not present a problem, this step may be omitted. 

Morgan KT, Thomas DA, St. Clair MB. 1989. Enzyme markers for studies of olfactory epithelial regeneration in rats exposed to methyl bromide [Abstract], Toxicologist 9 37. 

During cell fractionation, it is very important to analyze the purity of the fractions obtained. Whether or not the intended organelle is present in a particular fraction, and whether or not the fraction contains other components, can be determined by analyzing characteristic marker molecules. These are molecules that occur exclusively or predominantly in one type of organelle. For example, the activity of organelle-specific enzymes (marker enzymes) is often assessed. The distribution of marker enzymes in the cell reflects the compartmentation of the processes they catalyze. These reactions are discussed in greater detail here under the specific organelles. 

Olsen KM et al Effect of once-daily dosing vs. multiple daily dosing of tobramycin on enzyme markers of nephrotoxicity. Crit Care Med 2004 32 1678. [PMID 15286543]... 

Marvin-Sikkema FD, Lahpor GA, Kraak MN, Gottschal JC, Prins R (1992) Characterization of an anaerobic fungus from llama faeces. J Gen Microbiol 138 2235-2241 Muller M (1993) The hydrogenosome. J Gen Microbiol 139 2879-2889 Queiroz RC, Santos LM, Benchimol M (1991) Cytochemical localization of enzyme markers in Tritrichomonas foetus. Parasitol Res 77 561-566 Ribeiro , Monteiro-Leal LH, Benchimol M (2000) Contributions of the axostyle and flagella on the division process of Tritrichomonas foetus. J Eukaryot Microbiol 47 481-492... 

Treatment with a chemical substrate to reveal the location of the enzyme marker... 

Since none of the liposomal immunoassay approaches described in the scientific literature thus far took advantage of surface immobilization techniques, one could envision a double-amplification biosensor in which surface modification plays an important role [35]. For example, consider a dehydrogenase enzyme marker system which requires an electroactive cofactor such as NAD+. In the enzymatic reaction scheme ... 

The low-molecular-weight vitamin biotin is easily conjugated to antibodies and enzyme markers. Up to 150 biotin molecules can be attached to one antibody molecule, and the strong affinity of the biotin for the glycoprotein avidin allows its use as complex-ing secondary reagents. Biotin labeling of the primary (direct) or secondary (indirect) antibody can be used in the avidin-biotin methods. In the labeled avidin method the tracer is attached directly to the avidin molecule. In the avidin-biotin bridge method a biotinylated enzyme such as peroxidase is allowed to bind after attachment of avidin to the biotin-labeled antibody. 

Construction of amperometric immunosensors for the analysis of cholera antitoxin and comparison of the performances between three different enzyme markers... 

Amperometric current response to anti-CT using GOX-B and PPO-B as enzyme markers of the immunosensors... 

Enzyme marker Substrate Detection limit (fig/ml) Imax (MA/ cm2) Linear range(jja/ml) R2 Sensitivity (nA/jig ml/cm2)... 

CYP enzyme Marker reaction Inhibitor HLM IC50 (pM) rCYPs rCYPse ... 

Antigens can he present in intestinal lymphoid tissue by the transport of macros molecules across M-cells. Hie enzyme marker horseradish peroxidase is trans-... 

Ca2 +-ATPase has been used as an enzymic marker for the brush border of H. diminuta, although its precise function is open to question. Two forms of this enzyme occur within the tegument of the parasite. One appears to be calmodulin dependent and is active at a higher pH than the other (Table 6.2). Calmodulin appears to be a ubiquitous Ca2 + receptor which plays a part in most of the Ca2+-regulated processes that have been studied in eukaryotic cells. It is a highly conserved protein, so it is not surprising that... 

While enzymes may be covalently attached directly to primary probe molecules, as noted above for reasons of reagent versatility, steric factors, and potential signal amplification, indirect detection systems appear to be the more popular. Consequently, enzyme-probe conjugates are typically complexes of a desired enzyme marker and a secondary level probe that is, a probe molecule that can specifically identify a primary level probe molecule, such as an alkaline phosphatase-streptavidin conjugate can identify a biotinylated nucleic acid probe by virtue of the binding affinity between streptavidin and biotin. Other examples of enzyme-probe systems are given in the preceding section on direct and indirect detection systems. 

Enzyme markers and associated substrates are selected for several properties, including stability and a low detection limit. 

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