The Purification and Characterization of the Dextranase of Chaetomium gracile

Dextranase (EC 3.2.1.11) produced by Chaetomium gracile was purified by sequential chromatographies on CM- and DEAE-cellulose columns, and two active fractions, CD-I and CD-II, were isolated in electrophoretically pure states. The former fraction was obtained in a crystalline state. The estimated molecular weights were 77,000 for CD-I and 71,000 for CD-II, and their isoelectric points were 6.2 and 5.7, respectively. Both active fractions contained a sugar moiety (4.5%). Their amino acid compositions were determined. They were very similar to each other in enzymatic properties: The optimum pH was at around 5.5, and they were stable between pH 5.5 and 11.0, and at temperatures lower than 55°C. They were typical endodextranases, but their maximal degrees of dextran hydrolysis reached 55% as glucose.