Vitamin B-6 activity for rats of epsilon-pyridoxyllysine bound to dietary protein.
The biological activity of protein bound epsilon-pyridoxyllysine residues in a phosphopyridoxyl-bovine serum albumin (PP-BSA) preparation was evaluated. Previous studies have demonstrated that pyridoxal phosphate may bind to food proteins as epsilon-pyridoxyllysine complexes during processing and storage. The present research, employing PP-BSA as a model, was initiated to determine the nutritional consequences of epsilon-pyridoxyllysine formation in foods. The concentration of epsilon-pyridoxyllysine residues in the PP-BSA was determined spectrophotometrically and chromatographically. Rat bioassay of the PP-BSA revealed that epsilon-pyridoxyllysine exhibited 60% activity relative to the molar potency of pyridoxine. These results suggest the partial release of bound vitamin B-6 possibly by in vivo enzymatic hydrolysis of epsilon-pyridoxyllysine. The presence of PP-BSA in a test diet containing 0.25 microgram added pyridoxine per g of diet inhibited the utilization of approximately half of the free pyridoxine by the rats. It is postulated that the observed inhibition resulted from an antivitamin B-6 effect of intact epsilon-pyridoxyllysine. This effect requires further investigation.
D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001682:Biological Availability; D004044:Dietary Proteins; D006128:Growth / Q000187:drug effects; D008239:Lysine / Q000031:analogs & derivatives; D008297:Male; D011730:Pyridoxal / Q000031:analogs & derivatives* / Q000494:pharmacology; D011736:Pyridoxine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D012710:Serum Albumin, Bovine
D004044:Dietary Proteins; D012710:Serum Albumin, Bovine; C017696:epsilon-pyridoxyllysine; D011730:Pyridoxal; D001219:Aspartate Aminotransferases; D008239:Lysine; D011736:Pyridoxine