首页 | 本学科首页   官方微博 | 高级检索  
   检索      


PURIFICATION AND CHARACTERIZATION OF CARNOSINE SYNTHETASE FROM MOUSE OLFACTORY BULBS
Authors:Hiroo  Horinishi  Mary  Grillo Frank L  Margolis
Institution:Department of Physiological Chemistry and Pharmacology, Roche Institute of Molecular Biology, Nutley, NJ 07110, U.S.A.
Abstract:Carnosine synthetase was purified about 500-fold from mouse olfactory bulb to a specific activity of approx 25 nmol/min/mg. This is an increase of 800-fold over that previously reported for this enzyme from rat brain and 11 times higher than the most highly purified enzyme from chicken pectoral muscle. ATP was essential for activity and could not be replaced by ADP. NAD had no effect on the synthesis of carnosine. Of the β-alanine analogues tested, the purified mouse enzyme incorporated only γ-aminobutyric acid and β-amino-n-butyric acid into peptide linkage with histidine. Synthesis of carnosine by the mouse olfactory bulb enzyme was competitively inhibited by the histidine analogues, 1-methyl histidine and 3-methyl histidine, with Ki values which were at least 40 times the Km value for histidine (16 μM). Ornithine and lysine were more efficient β-alanine acceptors than 1-methyl histidine for the mouse enzyme. Enzyme from olfactory epithelium and leg skeletal muscle of mice also showed higher Ki values for 1–methyl histidine than the Km value for histidine. In contrast, carnosine-anserine synthetase from chicken pectoral muscle gave Km values for histidine, 1-methyl histidine and 3-methyl histidine, which were all in the range of 4–12 μM. The differences in substrate specificity between the enzyme from mouse and chicken implies alternate routes of anserine synthesis in these species and predicts the occurrence of certain novel peptides in mouse brain.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号