Specificity, enzyme assay

The diagnosis of GAMT deficiency and AGAT deficiency and Cr transporter deficiency can be confirmed by specific enzyme assays. 

Mary Ellen Jones and her colleagues set out to purify the enzyme or enzymes involved in these two reactions. Their main goal was to determine whether the two reactions are carried out by one protein or more than one. Their findings indicated that the two reactions were both catalyzed by the same enzyme, consisting of a single polypeptide chain. To demonstrate this fact, it was necessary to monitor both enzyme activities at each step in the purification and show that both activities copurified. For this purpose, Jones used specific enzyme assays for both enzyme activities. All fractions were assayed for both enzymatic activities at each stage of the purification. 

Definitive diagnosis of a UCD can be made by specific enzyme assays. A deficiency of OTC,... 

In general, in any separation and purification procedure, the target molecule (a protein in this case) must be able to be identified by some physical or chemical property. This might be the red color of myoglobin or a specific enzyme assay. Separation of molecules is carried out by exploiting physical or chemical differences between proteins in a mixture. 

Due to the high competitiveness of the crop protection market, the research process from synthesis of new chemicals to promotion of lead compounds to the project phase has to be as streamlined as possible. It is imperative not only to eliminate compounds with weak efficacy or phytotoxicity but also chemicals with non-desirable MoA as early as possible from further evaluation and to concentrate on a few promising candidates. Besides phenotypical inspection of treated plants, the target site of a compound is usually determined with specific enzyme assays in test tubes or microtiter plates, which is a time consuming, labor- and costintensive process. It requires either purification of the respective enzyme from plants or preparation of the proteins by heterologous expression in, for example,... 

What specific enzyme assays are particularly useful in diagnosing liver damage or disease ... 

Hybrid probe—immunoassays are expected to find a specific niche in clinical analysis, especially as a means to adapt probe assays to existing immunoanaly2ers which are locked into a specific enzyme or fluorescence detection technology. Commercialization of the first of these assays is expected by the year 2000. 

A, basically the KB for an antagonist but specifically measured in a biochemical binding study (or enzyme assay). 

Agarwal et al. 1978), the quantification of these specific enzymes may indicate that exposure to endosulfan has occurred. Blood tests, such as decay curves for aminopyrine in plasma, which are semiquantitative indices of liver enzyme induction, have been used successfully in the past to demonstrate enzyme induction in pesticide-exposed workers. Because numerous chemicals found at hazardous waste sites also induce these hepatic enzymes, these measurements are not specific for endosulfan exposure. However, measurements of enzyme activity, together with the detection of the parent compound or its metabolites in tissue or excreta, can be useful indicators of exposure. All of these potential biomarkers require further verification in epidemiological studies. Further studies with focus on the development of methods to separate and measure the estrogenicity of endosulfan in in vitro assays would be valuable since these assays are more sensitive and discriminative than other conventional biomarkers. Preliminary results have been presented by Sonnenschein et al. (1995). 

Assays of ciguatoxin. Determination of ciguatoxin levels in fish was carried out in many laboratories by mouse assays. Enzyme immunoassay to screen inedible fish has been proposed by Hokama (9). No specific chemical assay has been developed, as information on functional groups suitable for fluorescence labeling is not available. Analyses conducted in the authors laboratory on remnant fish retrieved from patients meals indicated that ciguatoxin content as low level as 1 ppb could cause intoxication in adults. An extremely high sensitivity and a sophisticated pretreatment method will be required for designing a fluorometric determination method for the toxin. 

Several excellent reviews have been written over the last decade highlighting the many different kinase assay formats available and their application to specific enzymes [20-22]. This section will only briefly review the current formats used within the HTS environment. The reader section consult the above-mentioned references for greater detail of each of the formats. 

Production of acetate ester pheromone components utilizes an enzyme called acetyl-CoA fatty alcohol acetyltransferase that converts a fatty alcohol to an acetate ester. Therefore, alcohols could be utilized as substrates for both aldehyde and acetate ester formation. In some tortricids an in vitro enzyme assay was utilized to demonstrate specificity of the acetyltransferase for the Z isomer of ll-14 OH [66]. This specificity contributes to the final ratio of... 

Ripe tomato fruits accumulate significant amounts of lycopene, but only trace amounts of xanthophylls. Dharmapuri and others (2002) overexpressed the lycopene (3-cyclase (b-Lcy) and (3-carotene hydroxylase (b-Chy) genes under the control of the fruit-specific Pds promoter, and transgene and protein expression was followed through semiquantitative reverse- transcription PCR, Western blotting, and enzyme assays. Fruits of the transformants showed a significant increase of (3-carotene, (3-cryptoxanthin, and zeaxanthin the carotenoid composition of leaves remained unaltered, and the transgenes and the phenotype were inherited in a dominant Mendelian fashion. 

Luminometric assay of ATP can also be applied to measurement of other substrates such as ADP, AMP, and ATP-specific enzymes. Other examples are reported in Table 4. 

The relation between microbial diversity and soil functions is poorly understood because we cannot measure easily the microbial diversity, even if we can detect unculturable microorganisms by molecular techniques (Nannipieri et al. 2003). In addition, the present assays for measuring microbial functions determine the overall rate of entire metabolic processes, such as respiration, or specific enzyme activities, without identifying the active microbial species involved. The recent advances in RNA extraction from soil might permit us to determine active species in soil (Griffiths et al. 2000 Hurt et al. 2001). Further advances in understanding require us to determine the composition of microbial communities and microbial functions in microhabitats. 

The model immunoassay is the enzyme-linked immunosorbent assay (ELISA) in which a non-specific capture antibody is bound to a surface, such as a multi-well plate or small tube [13]. In the basic form of ELISA, a second antibody tagged with an enzyme interacts specifically with the analyte. The enzyme assay produces a colored product that is read with a spectrophotometer. There are many variations on the basic immunoassay format that serve to increase sensitivity, specificity, linear range, and speed. Many commercial instruments have been developed to take advantage of various technologies for reporter molecules. The immunoassay may be coupled to an electronic sensor and transducer, such as a surface acoustical wave (SAW) sensor. Electrochemiluminescence (ECL) is a method in which the detector antibody is tagged with a ruthenium-containing chelate [13-15]. When the tag is... 

Variations in the substrate specificity of enzymes derived from different sources does occur and cross-reactivity should always be checked when developing an enzymic assay. This includes an investigation of the interference from a variety of substances that may be present in the sample in addition to studies on amino acid specificity. 

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