INCORPORATION OF RADIOACTIVE PHOSPHATE INTO NON-NUCLEOTIDE PROTEIN-BOUND PHOSPHORUS FRACTIONS OF RESPIRING CAT BRAIN SLICES

Abstract

Slices of cat brain respiring in a Krebs–Ringer bicarbonate medium were found to incorporate inorganic phosphate labelled with P32 into two non-nucleotide protein-bound phosphorus fractions, which are referred to as the residue organic phosphorus (ROP) and the "phosphoprotein" (PP), respectively. The addition of glucose or mannose to the medium increased the incorporation into both fractions. The addition of fructose, galactose, pyruvate, lactate, succinate, or L-glutamate failed to increase the incorporation into either fraction.Anaerobic conditions, homogenization of the tissue, or the addition of a wide range of metabolic inhibitors (cyanide, azide, iodoacetate, fluoride, nembutal, malononitrile, chloretone) inhibited the incorporation. The incorporation was also inhibited by 2,4-dinitrophenol in concentrations that do not inhibit oxygen consumption.These results are compared and contrasted with previous findings on the incorporation of P32 into the lipid phosphorus and pentosenucleic acid of brain slices.