Amino acid dehydrogenases (L-amino acid: oxidoreductase deaminating EC 1.4.1.X) are members of the wider superfamily of oxidoreductases that catalyze the reversible oxidative deamination of an amino acid to its keto acid and ammonia with the concomitant reduction of either NAD+, NADP+ or FAD. These enzymes have been received much attention as biocatalysts for use in biosensors or diagnostic kit...

Like its homologs throughout the biological world, the L-isoaspartyl protein repair methyltransferase of Escherichia coli, encoded by the pcm gene, can convert abnormal L-isoaspartyl residues in proteins (which form spontaneously from asparaginyl or aspartyl residues) to normal aspartyl residues. Mutations in pcm were reported to greatly reduce survival in stationary phase and when cells were s...

The three-dimensional structures of two HPII variants, V169C and H392Q, have been determined at resolutions of 1.8 and 2.1 A, respectively. The V169C variant contains a new type of covalent bond between the sulfur atom of Cys(169) and a carbon atom on the imidazole ring of the essential His(128). This variant enzyme has only residual catalytic activity and contains heme b. The chain of water mo...

amino acid dehydrogenases (l-amino acid: oxidoreductase deaminating ec 1.4.1.x) are members of the wider superfamily of oxidoreductases that catalyze the reversible oxidative deamination of an amino acid to its keto acid and ammonia with the concomitant reduction of either nad+, nadp+ or fad. these enzymes have been received much attention as biocatalysts for use in biosensors or diagnostic kit...

Wild-type Escherichia coli HPII catalase (heme d containing) has 15% the activity of beef liver enzyme per heme. The rate constant for compound I formation with H2O2 is 1.3 x 10(6) M(-1) s(-1). HPII compound I reacts with H2O2 to form O2 with a rate constant of 1.8 x 10(6) M(-1) s(-1). Forty percent of HPII hemes are in the compound I state during turnover. Compound I is reduced by ethanol and ...

It is now becoming generally noted that many diseases of hitherto unknown aetiology are due to inborn errors of metabolism in the sense in which Garrod (1923) used this term. Although these diseases cover the whole of medicine it has been particularly gratifying to note that mental disease, especially mental deficiency which currently is responsible for one of our main medical problems, has bee...

Cyanide forms an inhibitory complex with the haem d-containing E. coli catalase HPII, spectrally similar to the cyanide complex of beef liver enzyme but with absorption bands shifted 90 nm towards the red end of the spectrum. Both the Kd and Ki values are approximately 7 microM in the wild-type enzyme. The cyanide reaction is slow, with a bimolecular 'on' constant approx. 2000 x smaller than th...

A bond between the N delta of the imidazole ring of His 392 and the C beta of the essential Tyr 415 has been found in the refined crystal structure at 1.9 A resolution of catalase HPII of Escherichia coli. This novel type of covalent linkage is clearly defined in the electron density map of HPII and is confirmed by matrix-assisted laser desorption/ionization mass spectrometry analysis of trypti...

1. NADPH binds to bovine catalase and to yeast catalases A and T, but not to Escherichia coli catalase HPII. The association was demonstrated using chromatography and fluorimetry. Bound NADPH fluoresces in a similar way to NADPH in solution. 2. Bound NADPH protects bovine and yeast catalases against forming inactive peroxide compound II either via endogenous reductant action or by ferrocyanide ...

Vitamin B 6 is an important vitamin for normal brain function. The metabolism of dietary vitamin B 6 to its active cofactor pyridoxal 5´-phosphate is described. The mechanism of action of pyridoxal 5´-phosphate is described, as are some important functions in the brain. The clinical features and biochemistry of three inborn errors of metabolism affecting brain pyridoxal 5´-phosphate concentrati...