A facile purification of Leuconostoc mesenteroides B-512FM dextransucrase

Leuconostoc mesenteroides NRRL B-512F has been mutated by treatment with N-nitrosoguanidine. The resulting mutant (designated as B-512FM) produces 300 times as much enzyme as the parent strain. B-512FM dextransucrase was treated extensively with Sigma crude dextranase, followed by column chromatography on Bio-Gel A-5m. The purified dextransucrase had a specific activity of 84 IU/mg, a 100-fold purification with 42% yield, and was shown by SDS-PAGE to have a single protein of molecular weight of 158,000 with dextransucrase activity. The procedure has been used to produce purified enzyme for sequencing. The molecular weight of 158,000 agrees with that calculated from its amino acid sequence.