CHARACTERIZATION OF ALPHA-GLUCOSYLTRANSFERASE FROM PSEUDOMONAS-MESOACIDOPHILA-MX-45

alpha-Glucosyltransferase was purified from Pseudomonas mesoacidophila MX-45. The molecular weight was estimated to be 63,000 by SDS-PAGE, a nd the isoelectric point was pI 5.4. For enzyme activity based on sucr ose decomposition, the optimum pH and the optimum temperature were pH 5.8 and 40 degrees C, respectively. The ranges of stable pH and temper ature were pH 5.1-6.7 and below 40 degrees C, respectively. The purifi ed enzyme of MX-45 converted sucrose into trehalulose (1-O-alpha-D-glu copyranosyl-D-fructose) and isomaltulose (palatinose, 6-O-alpha-D-gluc opyranosyl-D-fructose) simultaneously, and the ratio of trehalulose to isomaltulose increased at lower reaction temperatures. Therefore, opt imum conditions for trehalulose production were pH 5.5-6.5 at 20 degre es C. The yield of trehallalose from sucrose (20-40% solution) was 91% . The K-m for sucrose was 19.2+/-3.3 mM estimated by the Hanes-Woolf p lot. Product inhibition was observed, and the product inhibition const ant was 0.17 M. Hg2+, Fe3+, Cu2+, Mg2+, Ag+, Pb2+, glucono-1,5-lactone , and Tris(hydroxymethyl)aminomethane inhibited the reaction.