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

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Abstract
Slices of cat brain respiring in a Krebs-Ringer bicarbonate medium were found to incorporate inorganic phosphate labeled with P32 into 2 non-nucleotide protein-bound P fractions, which are referred to as the residue organic P (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 incorporation into either fraction. Anaerobic conditions, homogenization of the tissue, or addition of a wide range of metabolic inhibitors (cyanide, azide, iodoacetate, fluoride, nembutal, malonitrile, chloretone) inhibited the incorporation, as did also 2,4-dinitrophenol in concentrations that do not inhibit O2 consumption. These results are compared and contrasted with previous findings on incorporation of P32 into the lipid P and pentosenucleic acid of brain slices.