Purification and characterization of protein methylase II from Helicobacter pylori

Protein methylase II (AdoMet:protein-carboxyl O-methyltransferase, EC 2.1.1 .24) was identified and purified 115-fold from Helicobacter pylori through Q-Sepharose ion exchange column, AdoHcy-Sepharose 4B column, and Superdex 2 00 HR column chromatography using FPLC. The purified preparation showed two protein bands of about 78 kDa and 29 kDa molecular mass on SDS PAGE. On no n-denaturing gel electrophoresis, the enzyme migrated as a single band with a molecular mass of 410 kDa. In addition, MALDI-TOF-MS analysis and Superd ex 200 HR column chromatography of the purified enzyme showed a major mass signal with molecular mass values of 425 kDa and 430 kDa, respectively. The refore, the above results led us to suggest thai protein methylase II purif ied from H. pylori is composed of four heterodimers with 425 kDa (4 x (78+2 9) = 428 kDa). This magnitude of molecular mass is unusual for protein meth ylases II so far reported. The enzyme has an optimal pH of 6.0, a K-m value of 5.0 x 10(-6) M for S-adenosyl-L-methionine and a V-max of 205 pmol meth yl-C-14 transferred min(-1) mg(-1) protein. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights r eserved.