Purified Dextransucrase from Leuconostoc mesenteroides NRRL B-640 Exists as Single Homogeneous Protein: Analysis by Non-denaturing Native-PAGE

Abstract

The extracellular dextransucrase from Leuconostoc mesenteroides NRRL B-640 was purified using polyethylene glycol (PEG-400) fractionation. A 25% (v/v) PEG-400 concentration gave dextransucrase with maximum specific activity of 9.2 U/mg with 16 fold purification in a single step. The purified enzyme by PEG-400 showed multiple protein bands on SDS-PAGE with one prominent band corresponding to the size 180 kDa (12). However, the same PEG-$00 fractionated dextransucrase samples showed single, intact and homogeneous band when analyzed on non-denaturing native-PAGE. This showed that dextransucrase remains in single molecular form in the native state and shows multiple forms only under denaturing conditions when it is heated before loading and when it contained SDS or 2-mercaptoethanol.