The binding of pyridoxamine 5-phosphate to the enzyme aspartate aminotransferase from pig heart was investigated by fluorescence spectroscopy. The substantial decrease in fluorescence intensity at 390 rnp that follows the interaction of pyridoxamine 5-phosphate with the apoenzyme was used to determine the alhnity constant. The effect of pH on the stability of the apoenzyme-pyridoxamine 5-phosph...

Background and Aims. Adipose tissue dysfunction results from many factors, including glycation-induced microvascular damages. We tested the usefulness of inhibiting methylglyoxal-induced glycation to adipose tissue microvasculature in this work, using the antioxidant and dicarbonyl scavenger drug pyridoxamine. Methods. A group of Wistar rats was treated daily with methylglyoxal (MG, 75 mg/Kg/da...

Although pyridoxal, pyridoxamine, and pyridoxine are all known to occur naturally (l), almost no information concerning the distribution of these individual forms of vitamin Bs is available. Use of three microorganisms for the individual detection of these three substances has been previously suggested (1, 2). Since Lactobacillus casei responds only to pyridoxal,’ this substance could be determ...

[3H]Pyridoxamine was orally administered to mice in physiological amounts, and the distribution of isotope between the six recognized forms of vitamin B6 and pyridoxic acid was determined at different times in the intestine, liver, blood, and brain. After 7 min about 50% of the radioactivity in pyridoxamine had been absorbed by the intestine and transported to the blood and other organs. Labele...

Tritium-labeled pyridoxamine, pyridoxal S/-phosphate, and pyridoxine 5’-phosphate were prepared and administered intravenously to mice, and the distribution of isotope in liver and carcass between pyridoxine, pyridoxine 5’-phosphate, pyridoxal, pyridoxal S/-phosphate, pyridoxamine, and pyridoxamine 5’-phosphate was determined at different times after administration. The vitamin B6 forms were ex...

The r&e of vitamin Bg in amino acid metabolism has been well established through enzyme studies (l-3) and by the substitution for various amino acids in growth studies (4-6). The coenzyme form, synthetic pyridoxal phosphate (7), functions as the coenzyme for amino acid decarboxylases (S-10), transaminases (2, 3), tryptophan formation (11)) and tryptophan breakdown by tryptophanase (12). The rea...

Streptococcus faecalis 8043 concentrates extracellular [3H]pyridoxal or [3H]pyridoxamine primarily as the corresponding 5'-phosphates. Accumulation of pyridoxamine requires an exogenous energy source and is inhibited by glycolysis inhibitors. A membrane potential is not required for transport of pyridoxamine, and an artificially generated potential does not drive uptake in this organism. Based ...

The classical studies of Rabinowitz and Snell (1) demonstrated that vitamin Be exists in at least three forms in the tissues of animals and plants: pyridoxine, pyridoxamine, and pyridoxal. Their assay procedure, a differential growth response of microorganisms to pyridoxine, pyridoxamine, and pyridoxal, would not differentiate between the phosphorylated and the nonphosphorylated forms of the vi...

1. Acetylation of aspartate aminotransferase from pig heart inhibits completely the enzymic activity when the coenzyme is in the amino form (pyridoxamine phosphate) or when the coenzyme has been removed, but not when the coenzyme is in the aldehyde form (pyridoxal phosphate). 2. The group the acylation of which is responsible for the inhibition has been identified with the in-amino group of a l...

Tritium-labeled pyridoxamine, pyridoxal S/-phosphate, and pyridoxine 5’-phosphate were prepared and administered intravenously to mice, and the distribution of isotope in liver and carcass between pyridoxine, pyridoxine 5’-phosphate, pyridoxal, pyridoxal S/-phosphate, pyridoxamine, and pyridoxamine 5’-phosphate was determined at different times after administration. The vitamin B6 forms were ex...