Stimulation of fructose-1,6-biphosphatase activity and synthesis in the cerebral cortex of rats submitted to the convulsant methionine sulfoximine.
Purification of rat cerebral cortex fructose-1,6-biphosphatase (FBPase) was performed by substrate elution from phosphocellulose, followed by Sephadex G-200 column filtration. The purified enzyme exhibited an optimum at pH 7.5, and its catalytic properties were very similar to those of the purified whole-brain enzyme previously prepared by Majumder and Eisenberg in 1977. The isolated preparation was electrophoretically homogeneous. The molecular weight of the enzyme subunit was 40,000; the hydrophobic amino acids predominated with 592 residues, and tryptophan was not detected. Expressed as mumol fructose-1,6-biphosphate hydrolysed per g brain tissue wet weight per min, FBPase activity increased twofold 24 h after an intraperitoneal injection of 100 mg per kg body weight of the convulsant methionine sulfoximine (MSO); the increase of the rate of incorporation of [1-14C]valine into brain FBPase was 2.8-fold under the same experimental conditions. A rabbit specific antiserum against rat cerebral cortex FBPase was prepared, and immunotitration studies confirmed both an increase in the number of molecules and the activation of brain FBPase, 24 h after administration of MSO. The increase of the number of brain FBPase molecules, induced by MSO, was due to an increase in synthesis of the enzyme, as shown by a double-label valine incorporation study.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D003292:Convulsants / Q000494:pharmacology*; D006597:Fructose-Bisphosphatase / Q000096:biosynthesis / Q000378:metabolism*; D008297:Male; D008717:Methionine Sulfoximine / Q000494:pharmacology*; D008970:Molecular Weight; D051381:Rats; D014633:Valine / Q000378:metabolism
D000596:Amino Acids; D003292:Convulsants; D008717:Methionine Sulfoximine; D006597:Fructose-Bisphosphatase; D014633:Valine