Malate dehydrogenase-lactate

Enzymes (malate dehydrogenase, lactate dehydrogenase, isocitrate dehydrogenase, citrate lyase)... 

Malate/oxalacetate Malate dehydrogenase/Lactate monooxygenase Oxygen electrode... 

G Wu, A Eiser, B ter Kuile, A Sail, M Muller. Convergent evolution of Trichomonas vaginalis lactate dehydrogenase from malate dehydrogenase. Proc Natl Acad Sci USA 96 6285-6290, 1999. 

The work in the biosensor industry permitted the testing and proved of stability and reproducibility of enzymes, within the conditions employed in that area. Enzymes with demonstrated stability include lactate oxidase, malate dehydrogenase, alcohol oxidase, and glutamate oxidase. 

The bioluminescent determinations of ethanol, sorbitol, L-lactate and oxaloacetate have been performed with coupled enzymatic systems involving the specific suitable enzymes (Figure 5). The ethanol, sorbitol and lactate assays involved the enzymatic oxidation of these substrates with the concomitant reduction of NAD+ in NADH, which is in turn reoxidized by the bioluminescence bacterial system. Thus, the assay of these compounds could be performed in a one-step procedure, in the presence of NAD+ in excess. Conversely, the oxaloacetate measurement involved the simultaneous consumption of NADH by malate dehydrogenase and bacterial oxidoreductase and was therefore conducted in two steps. 

Figure 5. Example of dehydrogenase reactions which can be coupled with the bienzymatic bacterial bioluminescent system. ADH = alcohol dehydrogenase (EC 1.1.1.1), SDH = sorbitol dehydrogenase (EC 1.1.1.14), LDH = lactate dehydrogenase (EC 1.1.1.27), MDH = malate dehydrogenase (EC 1.1.1.37).

Domain 1 Greek key helix bundle Domain 2 miscellaneous antiparallel a Dehydrogenases, see Alcohol, Glyceraldehyde phosphate, Malate, or Lactate... 

Lactate, malate dehydrogenase Liver alcohol dehydrogenase Clyceraldehyde-phosphate dehydrogenase Proteases... 

Madern D, Cai X, Abrahamsen MS, Zhu G (2004) Evolution of Cryptosporidium parvum lactate dehydrogenase from malate dehydrogenase by a very recent event of gene duplication. Mol Biol Evol 21 489-497... 

In the Korkes and Ochoa (11) mechanism proposed for the malo-lactic reaction (see top of next page), pyruvic acid is either a short-lived, fleeting intermediate, or it is bound to malic enzyme so that as soon as it is formed by the enzyme, it is converted to lactic acid by lactate dehydrogenase. [Both malic enzyme ( malic ) and malate dehydrogenase (de-... 

Some enzymes contain bound NAD+ which oxidizes a substrate alcohol to facilitate a reaction step and is then regenerated. For example, the malolactic enzyme found in some lactic acid bacteria and also in Ascaris decarboxylates L-malate to lactate (Eq. 15-12). This reaction is similar to those of isocitrate dehydrogenase,110-112 6-phosphogluconate dehydrogenase,113 and the malic enzyme (Eq. 13-45)114 which utilize free NAD+ to first dehydrogenate the substrate to a bound oxoacid whose (3 carbonyl group facilitates decarboxylation. Likewise, the bound NAD+ of the malolactic... 

The ratio [NAD+]/[NADH] appears to be maintained at a relatively constant value and in equilibrium with a series of different reduced and oxidized substrate pairs. Thus, it was observed that in the cytoplasm of rat liver cells, the dehydrogenations catalyzed by lactate dehydrogenase, sn-glycerol 3-phosphate dehydrogenase, and malate dehydrogenase are all at equilibrium with the same ratio of [NAD+]/[NADH].166 In one experiment rat livers were removed and frozen in less than 8 s by "freeze-clamping" (Section L,2) and the concentrations of different components of the cytoplasm determined167 the ratio [NAD+] / [NADH] was found to be 634, while the ratio of [lactate]/[pyruvate] was 14.2. From these values an... 

Malate dehydrogenase is structurally and mechanistically very similar to the lactate enzyme. 

A key structural and mechanistic feature of lactate and malate dehydrogenases is the active site loop, residues 98-110 of the lactate enzyme, which was seen in the crystal structure to close over the reagents in the ternary complex.49,50 The loop has two functions it carries Arg-109, which helps to stabilize the transition state during hydride transfer and contacts around 101-103 are the main determinants of specificity. Tryptophan residues were placed in various parts of lactate dehydrogenase to monitor conformational changes during catalysis.54,59,60 Loop closure is the slowest of the motions. 

All malate dehydrogenases have an arginine residue at position 102, whereas most lactate dehydrogenases have a glutamine at this position. Mutation of Gin —> Arg-102 in lactate dehydrogenase increases the activity toward oxaloac-etate by a factor of 103 and decreases the activity toward pyruvate by 104 i.e., a... 

RNS, ribonuclease LZM, lysozyme SNS, staphylococcal nuclease LZ4, T4 lysozyme PAP, papain TLS, thermolysin, TRX, thioiedoxin FLN, flavodoxin ADH, alcohol dehydrogenase coenzyme domain AKN, adenyl kinase MDG, malate dehydrogenase TIM, triosephosphate isomerase SUB, subtilisin CPA, carboxypeptidase LDH, lactate dehydrogenase PGK, phosphoglycerate kinase GPD, glyceraldehyde 3-phosphate dehydrogenase, HKN, hexokinase. 

Katrlik et al. [63] L-Malate, l-lactate Wines L-Malate dehydrogenase or l-lactate dehydrogenase and diaphorase/covered by a dialysis membrane NAD+-modified graphite-2-hexadecanone composite electrode Hexacyanoferrate(III)... 

Albareda-Sirvent and Hart [65] L-Malate, l-lactate Wines Lactate oxidase or malate dehydrogenase/in sol-gel matrix Sol-gel thick-film printed graphite electrode (contained NAD+ for malate sensors)/+ 350 mV vs. Ag/AgCl for lactate sensor and -125 mV vs. Ag/ AgCl for malate Meldola s Blue (mediator for the dehydrogenase)... 

Sulfite modified enzyme electrode. (2) L-Lactate/L-malate/ sulfite multibiosensor L-lactate dehydrogenase/L-malate dehydrogenase/ sulfite oxidase surface-modified enzyme electrodes/enzymes were deposited on the composite electrodes and covered with a dialysis membrane ... 

Esti et al. [8] L-Lactate L-Malate Micro-malolactic fermentation in red wine Lactate oxidase/in a nylon membrane with glutaraldehyde or NAD(P)+-dependent l-malate dehydrogenase oxaloacetate decarboxylating/ immobilised in an aminopropyl glass beads reactor Platinum electrode/ +650mV vs. Ag/AgCl Phenazine methosulfate (for malate sensor)... 

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