title: Competitive inhibition of benzodiazepine binding by fractions from porcine brain.
abstract: Fractions of porcine cerebral cortex extract separated by molecular weight on a Sephadex G-75 column were tested for their activities and potencies to inhibit [3H]benzodiazepine binding to rat brain homogenates. The fractions spanned molecular weights from 500 to 100,000. A potent inhibitor (benzodiazepine-competitive factor I, BCF-I) was discovered in the fraction containing substances with molecular weights from 40,000 to 70,000. Equilibrium binding studies indicated that BCF-I was a competitive inhibitor, making it a candidate as a benzodiazepine endogenous factor or profactor. BCF-I was heat stable, but trypsin digestion destroyed its activity. Another inhibitory fraction (BCF-II) was 1/5th as active as BCF-I and contained substances with molecular weights from 1000 to 2000.
mesh_terms: D000818:Animals; D001569:Benzodiazepines / Q000378:metabolism*; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism; D003975:Diazepam / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011955:Receptors, Drug / Q000378:metabolism*
chemical_list: D009419:Nerve Tissue Proteins; D011955:Receptors, Drug; D001569:Benzodiazepines; D003975:Diazepam