1. Pig heart mitochondrial malate dehydrogenase incubated with pyridoxal 5'-phosphate at pH 8.0 and 25 degrees C gradually loses activity. Such inactivation can be largely reversed by dialysis or by addition of L-lysine or L-cysteine, and can be made permanent by NaBH4 reduction. 2. Modification of malate dehydrogenase with pyridoxal 5'-phosphate at 35 degrees C involves two phases, an initial ...

We have found previously (Fahien, L.A., Kmiotek, E.H., MacDonald, M. J., Fibich, B., and Mandic, M. (1988) J. Biol. Chem. 263, 10687-10697) that glutamate-malate oxidation can be enhanced by cooperative binding of mitochondrial aspartate aminotransferase and malate dehydrogenase to the alpha-ketoglutarate dehydrogenase complex. The present results demonstrate that glutamate dehydrogenase, which...

2,4-Dihydroxybutyric acid (DHB) is a molecule with considerable potential as a versatile chemical synthon. Notably, it may serve as a precursor for chemical synthesis of the methionine analogue 2-hydroxy-4-(methylthio)butyrate, thus, targeting a considerable market in animal nutrition. However, no natural metabolic pathway exists for the biosynthesis of DHB. Here we have therefore conceived a t...

The effects of rotenone on the succinate-driven reduction of matrix nicotinamide nucleotides were investigated in Percoll-purified mitochondria from potato (Solanum tuberosum) tubers. Depending on the presence of ADP or ATP, rotenone caused an increase or a decrease in the level of reduction of the matrix nicotinamide nucleotides. The increase in the reduction induced by rotenone in the presenc...

Glucose transport by membrane vesicles isolated from Azotobacter uinelandii is coupled primarily to malate oxidation via a flavin-linked L-malate dehydrogenase. The addition of flavin adenine dinucleotide is required for malatedependent glucose transport but is not obligatory for malate oxidation. Both NADH and NADPH are oxidized by the vesicles at rates nearly identical with that of malate yet...

Many tissues which have been investigated have at least two malate dehydrogenase isoenzymes. One is an organelle form localized in mitochondrial fractions whereas the other does not appear to associate with organelles sedimenting after high speed centrifugation (17). Spinach leaf tissue has an additional malate dehydrogenase isoenzyme localized in the peroxisome or leaf microbody fraction (12, ...

Accumulation of oxidative damage has been implicated to be a major causative factor in the decline in physiological functions that occur during the aging process. The mitochondrial respiratory chain is a powerful source of reactive oxygen species (ROS), considered as the pathogenic agent of many diseases and aging. L-malate, a tricarboxylic acid cycle intermediate, plays an important role in tr...

The energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporati...

We have also examined similar parameters for several other enzymes; the trend suggests that in these cases there is a correlation between apparent association constant and capacity. These enzymes include yeast glutathione reductase, glucose 6-phosphate dehydrogenase, glutamate dehydrogenase, alcohol dehydrogenase and malate dehydrogenase, Neurospora crassa glutamate dehydrogenase, pig heart iso...

PURPOSE To determine whether activity of carbohydrate metabolism enzymes (aldolase, pyruvate kinase, isocitrate dehydrogenase, and malate dehydrogenase) are altered in the glaucomatous trabecular meshwork (TM) compared to controls. METHODS Tissue specimens were obtained from trabeculectomy (n=45 open angle glaucoma; Caucasian, average age 61+/-8 years of age of both genders) and from cadaver ...