title: Inhibition of brain tubulinyl-tyrosine carboxypeptidase by endogenous proteins.
abstract: When a 25-50% ammonium-sulphate-insoluble fraction from a bovine brain preparation was chromatographed on a cellulose phosphate column, several protein fractions which inhibit the activity of tubulinyl-tyrosine carboxypeptidase were obtained. One of these fractions exhibited activity of fructose-bisphosphate aldolase (EC 4.1.2.13) and the enzyme accounted for more than 95% of the protein of this fraction as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The inhibitory activities of the two protein fractions which had the highest activity per mg of protein were practically abolished by pretreatment with pronase; preincubation with trypsin, on the other hand, caused only a partial inactivation of the inhibitors. The inhibitory activities were little affected by heating at 90 degrees C for 5 min. Preincubation with purified tubulinyl-tyrosine carboxypeptidase caused a great decrease of the inhibitory activities of these two fractions, leaving open the possibility that these inhibitors act as substrates of the carboxypeptidase.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors*; D002384:Catalysis; D002417:Cattle; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D005634:Fructose-Bisphosphate Aldolase / Q000302:isolation & purification / Q000494:pharmacology; D006358:Hot Temperature; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000494:pharmacology*
chemical_list: D009419:Nerve Tissue Proteins; D002268:Carboxypeptidases; C023212:tyrosyltubulin carboxypeptidase; D005634:Fructose-Bisphosphate Aldolase