title: Pyridoxine kinase, pyridoxine phosphate phosphatase and pyridoxine phosphate oxidase activities in control and B-6-deficient rat liver and brain.
abstract: The levels of pyridoxal phosphate in plasma, liver and brain and the activities of pyridoxine kinase, pyridoxine phosphate phosphatase and pyridoxine phosphate oxidase in liver and brain were measured over a 6-week period in rats fed pyridoxine-sufficient and pyridoxine-deficient diets. Consistently significant differences in enzyme activities between the two groups of animals were found only in pyridoxine kinase indicating that this enzyme plays a key role during the development of vitamin B-6 deficiency. Relative to control animals, the decrease observed in liver pyridoxine kinase acivity in animals fed pyridoxine-deficient diets is much greater than the decrease in brain pyridoxine kinase activity (50% decrease versus a 14% decrease after 5 weeks). In light of the suggestion that phosphorylation and binding to proteins serve to prevent the diffusion of B-6 vitamers out of cells, the differential response of pyridoxine kinase activity in liver and brain may be important in the maintenance of the vitamin B-6 supply in the central nervous system. During the course of this study, a new method for the determination of cellular phosphatase activity on a phosphorylated form of vitamin B-6 was developed. 3H-C4'-Pyridoxine phosphate was used as substrate and was separated from 3H-C4'-pyridoxine by means of anion-exchange filter paper disks.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D009928:Organ Specificity; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011731:Pyridoxal Kinase / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D011734:Pyridoxaminephosphate Oxidase / Q000378:metabolism*; D051381:Rats; D026681:Vitamin B 6 Deficiency / Q000201:enzymology*
chemical_list: D011732:Pyridoxal Phosphate; D011734:Pyridoxaminephosphate Oxidase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D010770:Phosphotransferases; D011731:Pyridoxal Kinase; C027138:pyridoxine phosphate phosphatase; D010744:Phosphoric Monoester Hydrolases