PURIFICATION AND CHARACTERIZATION OF DEXTRANSUCRASE FROM LEUCONOSTOC MESENTEROIDES NRRL B-1149

摘要

Leuconostoc mesenteroides NRRL B-1149 produces extracellular dextransucrase which in this study was purified using different concentrations of polyethylene glycol (PEG). The dextran produced by this enzyme is unique in that it contains alpha -(1 arrow right 6) and alpha -(1 arrow right 3) linkages which have clinical applications. The cell free supernatant with 0.9 U/mg enzyme specific activity was subjected to fractionation by PEG-400 and PEG-1500. The 33% PEG-400 gave dextransucrase with specific activity of 9.2 U/mg and 10 fold purification and the 15% PEG-1500 gave dextransucrase with maximum specific activity of 15 U/mg and 17 fold purification in a single step. The purified enzyme showed multiple molecular forms on denaturing SDS-PAGE with three prominent bands. The purified dextransucrase confirmed the presence of glucan, after in-situ activity detection by Periodic acid Schiff's staining after running under denaturing SDS-PAGE. The three bands that appeared on denaturing SDS-PAGE stained with silver nitrate solution, corresponded to the three activity bands.