Vitamin B6 metabolism and binding to proteins in the blood of alcoholic and nonalcoholic men.
Blood obtained from nonalcoholic and alcoholic subjects was incubated with 100 nM [3H]pyridoxine to study its uptake and metabolism by erythrocytes and the binding of vitamin B6 metabolites to proteins in plasma and erythrocytes. Erythrocytes of the alcoholics accumulated tritium faster than those of the controls; however, they contained the same total amount of tritiated compounds by 15 min. After incubation for 30 min, the erythrocytes had converted most of the pyridoxine to pyridoxal phosphate and pyridoxal. Pyridoxal-P remained in the erythrocytes, and approximately 40% of the pyridoxal diffused into the plasma. [3H]Pyridoxal and [3H]pyridoxal-P levels in the erythrocytes and plasma of the alcoholics were similar to those in the controls. However, dialyzed hemolysates of the alcoholics had more [3H]pyridoxal and a lower percentage of [3H]pyridoxal-P than those of the controls. The total concentration of plasma pyridoxal-P was lower in the alcoholics than in the controls and did not change upon incubation of whole blood with pyridoxine or upon dialysis. The erythrocytes of the alcoholics and controls had similar concentrations of pyridoxal-P that increased 2.5-fold upon incubation of whole blood with pyridoxine for 30 min and returned to the initial concentrations upon dialysis. The amount of [3H]pyridoxal and [3H]pyridoxal-P bound to protein was assessed by treating hemolysate and plasma samples with borohydride before dialysis. More 3H was bound to protein in the erythrocytes than in the plasma. The amount of protein-bound 3H in the erythrocytes of the alcoholics was lower than that of the controls, whereas the amount of protein-bound 3H in plasma was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Fonda
M L
ML
Department of Biochemistry, University of Louisville Health Sciences Center, KY 40292.
D000328:Adult; D000437:Alcoholism / Q000201:enzymology* / Q000534:rehabilitation; D000445:Aldehyde Oxidoreductases / Q000097:blood; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D008099:Liver / Q000201:enzymology; D008297:Male; D010744:Phosphoric Monoester Hydrolases / Q000097:blood; D011485:Protein Binding / Q000502:physiology; D011731:Pyridoxal Kinase / Q000097:blood; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000097:blood; D011736:Pyridoxine / Q000097:blood*; D026681:Vitamin B 6 Deficiency / Q000175:diagnosis / Q000201:enzymology*
D011732:Pyridoxal Phosphate; D000445:Aldehyde Oxidoreductases; C034030:pyridoxal oxidase; D011731:Pyridoxal Kinase; C027138:pyridoxine phosphate phosphatase; D010744:Phosphoric Monoester Hydrolases; D011736:Pyridoxine; C024593:pyridoxine 5-phosphate