Enzymes colorimetric assay

Detergent should be inexpensive Detergent should be easily removable Detergent should not interfere with assays such as lipid and protein colorimetric assays and enzyme assays... 

A colorimetric assay for lecithin and choline was described by Kotsira and Klonis (1998) using two enzymes (phospholipase and choline oxidase) and an indicator dye conjugate (bromothymol blue-glutathione) co-immobilised on a glutaraldehyde-activated polyacrylamide transparent gel. The change of the... 

Biomedical analytical chemistry happens to be one of the latest disciplines which essentially embraces the principles and techniques of both analytical chemistry and biochemistry. It has often been known as clinical chemistry . This particular aspect of analytical chemistry has gained significant cognizance in the recent past by virtue of certain important techniques being included very much within its scope of analysis, namely colorimetric assays, enzymic assays, radioimmunoassays and automated methods of clinical analysis. 

Colorimetric Assays Involving Redox Reactions, and (iv) Colorimetric Assays of Enzyme Levels. 

A few typical examples of colorimetric assay of enzyme levels will be discussed briefly hereunder ... 

Clinical chemistry Enzyme rate assays, colorimetric assays, end-point assays, immunoassays Upstone, 2000 ... 

Additionally, we tested cell extracts in the colorimetric assay both negative control strains E. coli pET28a containing the empty vector and E. coli BFDL476Q (Table 2.2.1.2) did not show any enzyme activity in the TTC assay, whereas E. coli BAL (Table 2.2.1.2) led to the formation of an intense red color (data not shown). 

The simplest, but least accurate, method of assaying DPO activity is to record the final color yield when the enzyme is incubated with a suitable chromogenic substrate such as catechol, DOPA, or 4-methylcatechol. DOPA is the most frequently used substrate in colorimetric assays because it yields a dark brown/black end-product. In this reaction, catecholase catalyzes the conversion of DOPA to dopaquinone and then to the red dopachrome, which subsequently polymerizes to yield dark brown melanin-type pigments. Unfortunately, this simple procedure has serious limitations, as it measures the end-product of a sequence of reactions rather than the true initial reaction rate. Furthermore, because different substrates yield different final colors, valid kinetic comparisons between substrates are not possible. Nevertheless, this simple assay technique has proved adequate for useful comparative studies of the levels of enzymic browning in different fruit varieties and similar problems (Vamos-Vigyazo, 1981 Machiex et al., 1990). 

Protein phosphatase inhibition is usually detected by colorimetric methods, but the development of a biosensor requires the search of other transduction techniques. Electrochemistry has been widely used in biosensors because of the simplicity, easy to use, portability, disposability and cost-effectiveness of the devices. As protein phosphatase is not an oxidoreductase enzyme, our work has been devoted to the investigation of novel enzymatic substrates, electrochemically active only after their dephosphorylation by the protein phosphatase. Nevertheless, colorimetric assays have been used for the optimisation of several experimental parameters. 

Routine qualitative and quantitative biochemical analysis including many colorimetric assays. Enzyme assays, kinetic studies, and difference spectra. 

Figure 3. Alcohol oxidase stabilization by mono-, di-, and trisaccharides. Sugars were added to the enzyme at concentrations of 1—10% immediately prior to drying. The solutions were dried in shallow dishes at 30 C under a vacuum and then harvested, ground to a powder, and stored in vials at 37 C. Enzyme activity was assayed with methanol as a substrate using an oxygen electrode and colorimetric assay.

MTT assay is a standard colorimetric assay used to determine cytotoxicity of potential medicinal agents and other toxic materials. It is based on the reduction of the tetrazolium salt MTT by viable cells. A mitochondrial dehydrogenase enzyme is able to cleave the tetrazolium rings of the pale yellow MTT and form dark purple formazan crystals, which are largely impermeable to cell membranes resulting in the accumulation of these crystals within healthy cells. Solubilization of the cells by the addition of a detergent results in the liberation of crystals, which are solubilized. The metabolic activity of cells is directly proportional to the concentration of the created formazan product (22), whose color is quantified in a colorimetric assay. 

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