To understand the catalytic mechanism of glycogen phosphorylase (EC 2.4.1.1), pyridoxal(5')phospho(1)-beta-D-glucose was synthesized and examined as a hypothetical intermediate in the catalysis. Pyridoxal phosphoglucose bound stoichiometrically to the cofactor site of rabbit muscle phosphorylase b in a similar mode of binding to the natural cofactor, pyridoxal 5'-phosphate. The rate of binding ...

Pig muscle phosphoglucose isomerase modified with pyridoxal 5'-phosphate under conditions that cause at least 90% inactivation of its catalytic activity was found to incorporate about 1.5 eq of pyridoxal 5'-phosphate per subunit. After digestion with thermolysin, two pyridoxal 5'-phosphate-containing peptides were isolated and their amino acid sequences were determined to be Leu-Gly-pyridoxyl-L...

The binding of rat liver glucocorticoid.receptor complexes to DNA-cellulose and nuclei has been studied after activation of the complexes by heating. Subsequent exposure to pyridoxal 5'-phosphate or pyridoxal markedly inhibited this binding. In one system 0.75 mM pyridoxal 5'-phosphate or 6.5 mM pyridoxal gave 50% inhibition. Pyridoxamine 5'-phosphate, pyridoxamine, and pyridoxine did not inhib...

1. l-Serine O-sulphate and l-threonine O-sulphate are degraded in the presence of pyridoxal 5'-phosphate to yield equimolar amounts of the corresponding keto acid, ammonia and sulphate. 2. Pyridoxal catalyses the same reactions at a faster rate. 3. One of a number of bi- or ter-valent metal ions must be present for these degradations to proceed. The reaction rates are dependent on a number of f...

Pyridoxal 5’.phosphate labeled to the extent of 90%’ with 13C in the 4’ (aldehyde) and 5’ (methylene) positions has been synthesized. 13C NMR spectra of this material and of natural abundance pyridoxal 5’.phosphate are reported, as well as r3C NMR spectra of the Schiff base formed by reaction of pyridoxal 5’.phosphate with n-butylamine, the secondary amine formed by reduction of this Schiff bas...