The effect of pyridoxal 5'-phosphate on the 1,25-dihydroxyvitamin D3 receptor system has been studied by using pig intestinal chromatin. Pyridoxal 5'-phosphate did not affect the binding of 1,25-dihydroxyvitamin D3 to its receptor extracted from chromatin with hypertonic KCl, although in the presence of pyridoxal 5'-phosphate 1,25-dihydroxyvitamin D3-receptor complexes were not readily precipit...

1. Phospholipase C was inactivated by exposure to the three amino-group reagents, ethyl acetimidate, 2,4,6-trinitrobenzenesulphonic acid and pyridoxal 5'-phosphate plus reduction. 2. Inactivation by pyridoxal 5'-phosphate showed the characteristics of Schiff's base formation with the enzyme. The pyridoxal 5'-phosphate-treated enzyme after reduction had an absorbance maximum at 325nm and 6-N-pyr...

Vitamin B6 concentrations in patients with chronic liver disease and hepatocellular carcinoma Vitamin B6 is the generic term for three closely related and interconvertible compounds. Most of the vitamin B6 obtained from the diet is rapidly converted by the liver to its active coenzyme, pyridoxal-5-phosphate, which has a central role in the metabolism of amino acids. Patients with chronic liver ...

Saccharopine dehydrogenase (EC 1.5.1.7) from bakers’ yeast was reversibly inactivated by pyridoxal and pyridoxal 5’-phosphate. The inactivation by pyridoxal 5’-phosphate was accompanied by the appearance of a peak at 428 nm, which was shifted to 325 nm upon reduction with NaBH4. Paper chromatography of an acid hydrolysate of the pyridoxal 5’-phosphate-treated, NaBH4-reduced enzyme showed the pr...

The nuclear fraction of rat hepatoma-derived HTC cells contained approximately 8% of the total cellular pyridoxal 5'-phosphate. HTC cells were able to metabolize [3H]pyridoxine to coenzymatically active pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate. As HTC cells did not have any demonstrable pyridoxine-5'-phosphate oxidase activity, the conversion of pyridoxine to pyridoxal 5'-phosphate ...

The stimulation of the carboxylase reaction by effectors of ribulose 1,5-bisphosphate carboxylase/oxygenase displays higher sensitivity towards pyridoxal 5'-pyridoxal 5'-phosphate inhibition than the catalytical process itself. Pyridoxal 5'-phosphate binding to the enzyme is not affected by the modulators 6-phosphogluconate and fructose 1,6-bisphosphate at low concentrations at which these agen...

glucose 6- phosphate dehydrogenase from streptomyces aureofaciens was purified andinactivated by pyridoxal 5′-phosphate (plp). the inactivation was a pseudo-first order and time-dependentreaction. complete inactivation was achieved at 0.2mm plp within 16 minutes. the type of inhibition wascompetitive with respect to glucose 6- phosphate. spectral characteristics of plp-enzyme complexcorresponde...

The concentrations of pyridoxal 5'-phosphate, and the holoenzyme activities and apoenzyme contents of alanine aminotransferase and aspartate aminotransferase in plasma were determined simultaneously in healthy individuals, patients with renal insufficiency with and without chronic haemodialysis and in patients with acute myocardial infarction. Plasma pyridoxal 5'-phosphate is significantly dimi...

The enzyme mitochondrial aspartate aminotransferase from beef liver is a dimer of identical subunits. The enzymatic activity of the resolved enzyme is restored upon addition of the cofactor pyridoxal 5-phosphate. The binding of 1 molecule of cofactor restores 50% of the original enzymatic activity, whereas the binding of a 2nd molecule of cofactor brings about more than 95% recovery of the cata...