title: Characterization and substrate specificity of a protein carboxymethylase in the pituitary gland.
abstract: Protein carboxymethylase, an enzyme capable of methylating proteins and polypeptides, was purified from bovine pituitary. The anterior pituitary hormones, luteinizing hormone, follicle-stimulating hormone, adrenocorticotropic hormone, growth hormone, thyroid-stimulating hormone, and prolactin, were found to be substrates for this enzyme. The posterior pituitary hormones, oxytocin and vasopressin, did not serve as substrates. With luteinizing hormone as the substrate, protein carboxymethylase had a pH optimum near pH 5.5. A limiting K(m) of 1.47 muM for S-adenosyl-L-methionine was obtained with luteinizing hormone as the methyl acceptor. Possible roles of this enzyme in the posterior and anterior pituitary are discussed.
mesh_terms: D000324:Adrenocorticotropic Hormone; D000645:Ammonium Sulfate; D000818:Animals; D002384:Catalysis; D002417:Cattle; D011232:Chemical Precipitation; D002845:Chromatography; D002848:Chromatography, DEAE-Cellulose; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007986:Luteinizing Hormone; D008722:Methods; D008780:Methyltransferases / Q000302:isolation & purification; D010047:Ovalbumin; D010121:Oxytocin; D010455:Peptides; D010902:Pituitary Gland / Q000201:enzymology*; D010907:Pituitary Hormones; D011388:Prolactin; D011506:Proteins; D012436:S-Adenosylmethionine; D012710:Serum Albumin, Bovine; D013972:Thyrotropin; D014667:Vasopressins
chemical_list: D010455:Peptides; D010907:Pituitary Hormones; D011506:Proteins; D014667:Vasopressins; D012710:Serum Albumin, Bovine; D010121:Oxytocin; D012436:S-Adenosylmethionine; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone; D010047:Ovalbumin; D008780:Methyltransferases; D000645:Ammonium Sulfate