We describe a convenient and simple continuous spectrophotometric method for the determination of mitogen-activated protein kinase (MAPK) kinase activity with its protein substrate. The assay relies on the measurement of phosphoprotein product generated in the first step of the MAPK kinase reaction. Dephosphorylation of the phosphoprotein is coupled to a MAPK phosphatase to generate phosphate, ...

Antibiotics are one of the most common pharmaceutical products, used for the treatment of bacterial ,fungal and parasitic infections. Among antibiotics, tetracyclines are extensively used in both human and animal welfare. Hence the monitoring and estimation of the levels of tetracycline in pharmaceutical products and effluents have become a necessity for researchers and industries. Current meth...

A new assay for 3-hydroxy-3-methylglutaryl CoA reductase (mevalonate: NADP oxidoreductase [acylating CoA] , EC 1.1.1.34) is based upon the measurement of released coenzyme A (SH) during the reduction of 3-hydroxy-3-methylglutaryl CoA to mevalonate. Coenzyme A was measured in the presence of dithiothreitol, required for activity, by reaction with 5,5’-dithiobis(2-nitrobenzoic acid). Sodium arsen...

A cost-effective b[combining low line]a[combining low line]ttery-powered s[combining low line]pectrophotometric s[combining low line]ystem (BASS) was developed for quantitative point-of-care (POC) analysis on a microfluidic chip. By using methylene blue as a model analyte, we first compared the performance of the BASS with a commercial spectrophotometric system, and further applied the BASS for...

Simple spectrophotometric and spectrofluorimetric methods are suggested for the determination of antifungal drugs; clotrimazole, econazole nitrate, ketoconazole, miconazole and tolnaftate. Spectrophotometric one depends on the interaction between imidazole antifungal drugs as n-electron donor with the pi acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in methanol or with p-chloranilic ...

A multicommuted flow system with the propulsion device placed before detection is proposed for the determination of tartaric acid and free potassium in table and Port wines. A dialysis unit was introduced to increase sample dilution and minimize matrix interferences. The determination of tartaric acid was based on the spectrophotometric monitorization of the complex formed by the dialyzed analy...

Spectrophotometric determination of protein concentrations is an important analytical tool for nearly all phases of protein drug development and manufacturing. Determinations of absorptivities (A0.1%) and molar extinction coefficients (ε) for protein solutions require at least one initial, accurate measurement of protein concentration. Traditionally, this crucial concentration has been determin...

Vesicles prepared with the French press from membranes of cyanelles of Cyanophora paradoxa retain O(2) evolution activity with rates up to 500 micromoles 2,6-dichlorophenolindophenol reduced per hour per milligram chlorophyll. This activity is immediately lost when the vesicles are transferred from the sucrose-phosphate-citrate preparation buffer into dilute phosphate buffer. Similar preparatio...

Solid phase spectrophotometry (SPS) provides effective methods to combine metal ion preconcentration and their spectrophotometric determination, by integrating the formation of colored complexes and their fixation on the surface of a solid support placed inside the measurement cell. The coupling between flow injection analysis (FIA) and SPS (FI-SPS) makes it unnecessary to reach equilibrium con...

Three reliable, rapid and selective methods have been developed and validated for the determination of imipramine and chlordiazepoxide in pharmaceutical dosage forms. The first method is spectrophotometric method includes simultaneous estimation method, first order derivative spectrophotometric method, isoabsorptive method and multiwavelength method. All variables affecting the reaction have be...