ABSTRACT
The uptake, distribution, and metabolism of pyridoxine in human erythrocytes were determined by incubating isolated erythrocytes in isotonic sodium phosphate, pH 7.4, with [3H]pyridoxine. After 60 min at 37 degrees C, the erythrocytes had taken up approximately 80% of the radioactivity. At least 99% of the radioactivity in the erythrocytes was in the supernatant fraction of the cells and nearly 80% of that radioactivity was in pyridoxal-phosphate and was protein bound. The B6-protein complex was stabilized by reduction with borohydride. To identify the protein to which the radioactive B6 was bound, the hemolysate supernatant was fractionated by chromatography on DEAE Sephadex and carboxy methyl-cellulose. The protein fractions containing radioactivity were analyzed further by chromatography on Sephadex G-150. Most of the radioactive B6 was found to Hb. Thus human erythrocytes rapidly took up pyridoxine and converted it to pyridoxal-phosphate. Much of the newly synthesized pyridoxal phosphate was bound to Hb.
Subject(s)
Blood Proteins/metabolism , Erythrocytes/metabolism , Pyridoxine/blood , Humans , Protein Binding , Pyridoxal Phosphate/bloodSubject(s)
Corpus Luteum/metabolism , Prostaglandins E/metabolism , Prostaglandins F/metabolism , Receptors, Cell Surface/metabolism , Receptors, Prostaglandin/metabolism , Animals , Cattle , Cell Membrane/metabolism , Deoxycholic Acid/pharmacology , Female , Kinetics , Molecular Weight , Receptors, Prostaglandin/isolation & purification , Substrate SpecificityABSTRACT
RNA polymerase activity has been measured in liver and brain of C57BL-6J mice to determine if a change in enzyme activity can be correlated with decreasing survivorship of the animals. The RNA polymerases in tissue homogenates were solubilized by treatment with a buffer of high ionic strength and resolved by DEAE-Sephadex chromatography. Enzyme activity was quantitated by measuring the incorporation of [3H]UMP into RNA using heat denatured calf thymus DNA as the template. Statistically significant differences in polymerase activities were not observed in liver tissue from 18-, 25-, and 29-month-old animals or in brain tissue from 23- to 31-month-old animals. These age groups span the period of most rapid decrease in survivors,ip in our colony of mice (from 93% to 16%). The evidence indicates that changes in liver or brain RNA polymerase activities are not correlated with the rapid decrease in survivorship of these animals.