Through comparison with the high-resolution structure of Clostridium symbiosum glutamate dehydrogenase, the different substrate specificities of the homologous enzymes phenylalanine dehydrogenase and leucine dehydrogenase were attributed to two residues, glycine 124 and leucine 307, in Bacillus sphaericus phenylalanine dehydrogenase, which are replaced with alanine and valine in leucine dehydro...

Experiments do not support a recent claim that glutamate formed from the amination of citric acid cycle-derived alpha-ketoglutarate is a messenger in glucose-induced insulin secretion (Maechler, P., and Wollheim, C. (1999) Nature 402, 685-689). Glucose, leucine, succinic acid methyl ester, and alpha-ketoisocaproic acid all markedly stimulate insulin release but do not increase glutamate levels ...

1. The effect of pyridoxal 5'-phosphate on the activity of ox liver glutamate dehydrogenase towards different amino acid substrates was investigated. 2. Both alanine and glutamate activities decreased steadily in the presence of pyridoxal 5'phosphate. 3. The alanine/glutamate activity ratio increased as a function of inactivation by pyridoxal 5'-phosphate, indicating that glutamate activity is ...

The activation of NADHand NADPH-dependent glutamate dehydrogenase-catalyzed reactions appears to be similar for two structurally different compounds, ADP and any of a series of monocarboxylic L-a-amino acids. ADP and L-leucine have identical effects on a large variety of glutamate dehydrogenase-catalyzed reactions. Transient state studies show that L-leucine increases the rate of release of NAD...

Large-scale, microglass bead, continuous-flow electrophoresis was used to separate and collect protein fractions from a single serum sample. These fractions were assayed for a multiplicity of enzyme activities. Relatively good recovery was obtained with lactic acid dehydrogenase, leucine aminopeptidase, and phosphohexoseisomerase. Artifactually high recoveries were observed with aldotase and is...

Background Maple Syrup Urine Disease (MSUD) is a rare autosomal recessive metabolic error, characterized by Branched Chain α-Keto-acid Dehydrogenase Complex (BCKDC) deficiency. Mutations in 3 genes can lead to abnormal metabolism and accumulation of leucine, isoleucine, valine and corresponding keto-acids. MSUD affects 1 in 185,000 infants globally. Seizure is a common presentation among neonat...

The homodimeric enzyme form of quinoprotein ethanol dehydrogenase from Pseudomonas aeruginosa ATCC 17933 crystallizes readily with the space group R3. The X-ray structure was solved at 2.6 A resolution by molecular replacement. Aside from differences in some loops, the folding of the enzyme is very similar to the large subunit of the quinoprotein methanol dehydrogenases from Methylobacterium ex...

Glutamate dehydrogenase (NAD) activity was measured in liver and diaphragm mitochondria from 48 h fasted rats. Kinetic studies were performed with diaphragm enzyme and the effects of L-leu, ADP and L-ala on the K(1)m and V(1)max for NH(4)+, and α-ketoglutarate were evaluated. L-leucine increases by 2-8 fold the V(1)max for all three substrates with no significant changes in the K(1)m. ADP incre...

This is a method for measuring tripeptide aminopeptidase (EC 3.4.11.4) activity in serum. L- Leucylglycylglycine is used as substrate, and the reaction is followed by monitoring the absorbance increase at 340 nm when NAD+ is reduced to NADH in the presence of an excess of leucine dehydrogenase. This principle allows kinetic determination of the enzyme without interference by carboxypeptidases. ...