Glucose lactate dehydrogenase

Many dehydrogenase enzymes catalyze oxidation/reduction reactions with the aid of nicotinamide cofactors. The electrochemical oxidation of nicotinamide adeniiw dinucleotide, NADH, has been studied in depthThe direct oxidation of NADH has been used to determine concentration of ethanol i s-isv, i62) lactate 157,160,162,163) pyTuvate 1 ), glucose-6-phosphate lactate dehydrogenase 159,161) alanine The direct oxidation often entails such complications as electrode surface pretreatment, interferences due to electrode operation at very positive potentials, and electrode fouling due to adsorption. Subsequent reaction of the NADH with peroxidase allows quantitation via the well established Clark electrode. 

Liver function, including AST, ALT, alkaline phosphatase, lactate dehydrogenase (LDH), total and conjugated bilirubin a comprehensive metabolic panel can be ordered (i.e., sodium, potassium, chloride, bicarbonate, blood urea nitrogen, creatinine, glucose, calcium, AST, ALT, alkaline phosphatase, albumin, and total bilirubin), but phosphorus, magnesium, and fractionated... 

Figure 6.1 Pathways involved in glucose oxidation by plant cells (a) glycolysis, (b) Krebs cycle, (c) mitochondrial cytochrome chain. Under anoxic conditions. Reactions 1, 2 and 3 of glycolysis are catalysed by lactate dehydrogenase, pyruvate decarboxylase and alcohol dehydrogenase, respectively. ATP and ADP, adenosine tri- and diphosphate NAD and NADHa, oxidized and reduced forms of nicotinamide adenine dinucleotide PGA, phosphoglyceraldehyde PEP, phosphoenolpyruvate Acetyl-CoA, acetyl coenzyme A FP, flavoprotein cyt, cytochrome e, electron. (Modified from Fitter and Hay, 2002). Reprinted with permission from Elsevier...

Drug/Lab test interactions Tinidazole may interfere with certain serum chemistry values, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), triglycerides, and hexokinase glucose. 

When animal tissues cannot be supplied with sufficient oxygen to support aerobic oxidation of the pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by the reduction of pyruvate to lactate. As mentioned earlier, some tissues and cell types (such as erythrocytes, which have no mitochondria and thus cannot oxidize pyruvate to C02) produce lactate from glucose even under aerobic conditions. The reduction of pyruvate is catalyzed by lactate dehydrogenase, which forms the l isomer of lactate at pH 7 ... 

Lactate consumption The direction of the lactate dehydrogenase reaction depends on the relative intracellular concentrations of pyruvate and lactate, and on the ratio of NADH/NAD+ in the cell. For example, in liver and heart, the ratio of NADH/NAD+ is lower than in exercising muscle. These tissues oxidize lactate (obtained from the blood) to pyruvate. In the liver, pyruvate is either converted to glucose by gluconeogenesis or oxidized in the TCA cycle. Heart muscle exclusively oxidizes lactate to CO2 and H20 via the citric acid cycle. 

Figure 9-7 (A) Effect of glucose and glucose 6-phosphate concentrations on reaction rate of yeast hexokinase at equilibrium. Reaction mixtures contain 1-2.2 mM ATP, and 25.6 mM ADP at pH 6.5. From Fromm et al.51 (B) Effect of lactate and pyruvate concentrations on equilibrium reaction rates of rabbit muscle lactate dehydrogenase. Reaction mixtures contained 1.7 mM NAD+, and 30 - 46 pM NADH in Tris-nitrate buffer, pH 7.9, 25°C. From Silverstein and Boyer.53...

Fig. 22. Schematic presentation of the enzymatic synthesis of UDP-GalNH2 (33) including cofactor regeneration systems. A nucleoside monophosphate kinase (EC 2.7.7.4), B sucrose synthase (EC 2.4.1.13), C gal-l-P uridyltransferase (EC 2.7.7.12), D phosphoglucomutase (EC 2.7.5.1), E glucose-6-P dehydrogenase (EC 1.1.1.49), F lactate dehydrogenase (EC 1.1.1.27), G pyruvate kinase (EC 2.7.1.40) [319]...

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