Effects of epsilon-pyridoxyllysine bound to dietary protein on the vitamin B-6 status of rats.
The nutritional properties of protein bound epsilon-pyridoxyllysine residues in a phosphopyridoxyl bovine serum albumin (PP-BSA) preparation were examined by rat bioassay employing various levels of PP-BSA and pyridoxine (PN) fortification in the diets. Previous studies have shown that vitamin B-6 aldehydes can reductively bind to food proteins as epsilon-pyridoxyllysine complexes during processing and storage. The bound pyridoxyllysine was found to possess 50% molar vitamin B-6 activity, as indicated by slope ratios for rat growth, feed efficiency and liver pyridoxal 5'-phosphate concentration. The response curves indicated that high dosages of epsilon-pyridoxyllysine would fully satisfy the vitamin B-6 requirement. Direct antivitamin B-6 activity of epsilon-pyridoxyllysine was observed in diets containing low levels of PP-BSA. Classical rat acrodynia symptoms, depression of erythrocyte aspartate aminotransferase (AspAT) activity and elevation of in vitro coenzyme stimulation of AspAT were observed to be inversely related to PP-BSA concentration in the diet. The antivitamin B-6 effects were readily prevented by the presence of added 0.5--1.0 micrograms pyridoxing/g diet. In contrast to the previous study, the presence of PP-BSA in the diet did not inhibit the utilization of added PN. This difference was postulated to be due to a difference in vitamin B-6 concentration of the basal diets. The results of this study indicate that protein bound epsilon-pyridoxyllysine is nutritionally significant, presumably by its participation in the normal metabolism of vitamin B-6. The metabolic implications are discussed.
D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001681:Biological Assay; D001835:Body Weight / Q000187:drug effects; D004044:Dietary Proteins; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000201:enzymology; D008099:Liver / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D011485:Protein Binding; D011730:Pyridoxal / Q000031:analogs & derivatives* / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011736:Pyridoxine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D012710:Serum Albumin, Bovine / Q000494:pharmacology*
D004044:Dietary Proteins; D012710:Serum Albumin, Bovine; C017696:epsilon-pyridoxyllysine; D011730:Pyridoxal; D011732:Pyridoxal Phosphate; D001219:Aspartate Aminotransferases; D008239:Lysine; D011736:Pyridoxine; C024593:pyridoxine 5-phosphate