| euconostoc mesenteroides NRRL B-512FM dextransucrase was treated extensively with Sigma crude dextranase, followed by column chromatography on Bio-Gel A-5m. The purified dextransucrase has a specific activity of 84 IU/mg, and was shown by SDS-PAGE to have a single protein of 158 kDa with dextransucrase activity. The procedure gave a 100-fold purification with 42% yield, and was used to produce purified enzyme for sequencing.;The active site of dextransucrase was studied by chemical modification with diethyl pyrocarbonate and photo-dye-oxidation. Kinetic analysis of the inactivation data showed that two histidines are essential for the dextransucrase activity. We proposed that the two imidazolium groups of the histidines at the active site donate protons to the leaving fructose molecules during dextran synthesis.;The specificity of the acceptor binding site was studied with ;The acceptor product structures of maltodextrins with dextransucrase have been studied by using known specificities of porcine pancreatic... |
