Lactate, enzymatic analysis

W20. Williams, D. L., Doig, A. R., and Korosi, A., Electrochemical-enzymatic analysis of blood glucose and lactate. Anal. Chem. 42, 118-121 (1970). 

Vassault A (1983) Lactate dehydrogenase UV-method with pyruvate and NADH. In Bergmeyer HU, Bergmeyer J Grassl M (eds) Methods of Enzymatic Analysis. III. Enzymes 1 Oxidoreductases, Transferases, 3rd edn, pp. 118-126. Verlag-Chemie, Weinheim. 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

For most assays used to, determine the amount of a substance enzymatically, they are allowed to continue to completion so that all the substrate has been converted into a measurable product. These methods are called end point or, more correctly, equilibrium methods, because the reaction ceases when equilibrium is reached. Reactions in which the equi-hbrium point corresponds virtually to complete conversion of the substrate are obviously preferable for this type of analysis. However, unfavorable equilibriums can often be displaced in the desired direction by additional enzymatic or nonenzymatic reactions that convert or trap a product of the first reaction (e.g., in measuring lactate with lactate dehydrogenase, the pyruvate formed can be trapped by the addition of hydrazine, with which it forms an irreversible hydrazone.)... 

The importance of other factors additional to amount ofnecrosis has also been studied. In patients with first acute MI treated with PCI, LAD-related MI show for a similar amount of myocardial necrosis as determined by enzymatic infarct size, lower left-ventricular ejection fraction (LVEF) when compared to non-LAD-related MI. LVEF-measured 6-month post-MI showed a decrease, for every 1000 cumulative lactate dehydrogenase release, of 4.8% for LAD and 2.4% for non-LAD-related infarcts (p < 0.0001), and these results remain in the multivariate analysis (Elsman et al., 2006). 

Our laboratory has studied the stereochemistry of methyl group formation in a number of a, 0 elimination reactions of amino acids catalyzed by pyridoxal phosphate enzymes. The reactions include the conversions of L-serine to pyruvate with tryptophan synthase 02 protein (78) and tryptophanase (79), of L-serine and l-tyrosine with tyrosine phenol-lyase (80), and l-cystine with S-alkylcysteine lyase (81). In the latter study, the stereospecific isotopically labeled L-cystines were obtained enzymatically by incubation of L-serines appropriately labeled in the 3-position with the enzyme O-acetyl serine sulfhy-drase (82). The serines tritiated in the 3-position were prepared enzymatically starting from [l-3H]glucose and [l-3H]mannose by a sequence of reactions of known stereochemistry (81). The cysteines were then incubated with 5-alkyl-cysteine lyase in 2H20 as outlined in Scheme 19. The pyruvate was trapped as lactate, which was oxidized with K2Cr202 to acetate for analysis. Similarly, Cheung and Walsh (71) examined the conversion of D-serine to pyruvate with... 

Table 2 Comparison of the results obtained using the enzymatic and chromatographic methods for the analysis of various samples of D lactic acid obtained by fermentation. [L-lactate content = (L-lactic / L-lactic + D-lactic) x 100]... 

Flow injection analysis offers suitable systems for food sample analyses and can accommodate multiple samples. Moreover, sample pretreatment processes can be performed using flow systems in combination with FIA. Therefore, FIA systems have been developed for analyses of lactate in food using LOD and LDH. The enzymatic reactions of LOD and LDH are as follows ... 

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