Purification and properties of a new exo-(1-->3)-beta-D-glucanase from Bacillus circulans YK9 capable of hydrolysing resistant curdlan with formation of only laminari-biose.
A (1-->3)-beta-D-glucan glucanohydrolase (EC 3.2.1.6), capable of hydrolysing resistant curdlan, was purified chromatographically from the culture supernatant of Bacillus circulans complex YK9 on Toyopearl HW-55F and butyl-Toyopearl 650M columns. The purified enzyme had a specific activity of 190 units mg-1 on regenerated curdlan. The molecular mass was estimated to be about 70 kDa as judged by SDS-PAGE. The enzyme had a pH optimum of approximately pH 6.0. It hydrolysed regenerated and resistant curdlans yielding predominantly laminari-biose, although the rate of hydrolysis of the former was much higher than the latter. This enzyme rapidly hydrolysed laminaran, curdlan and carboxymethyl-curdlan, but did not cleave schizophyllan and screloglucan, which have glucosyl side chains. The enzyme hydrolysed low molecular mass (1-->3)-beta-D-glucans-(mean degree of polymerization, DPn = 131, 49 and 14) and laminari-heptaose more efficiently than curdlan. It also hydrolysed laminari-hexaose and -pentaose effectively, but laminari-tetraose only slightly and it did not hydrolyse laminari-triose or -biose. The enzyme is an exo-hydrolase of curdlan and various oligomers composed of (1-->3)-beta-D-glucosidic linkages, liberating laminari-biose from their non-reducing terminals. The laminari-biose generated was in the alpha-form.
Kobe Women's University, Japan.
Y
Y
Kanzawa
T
T
Kurasawa
Y
Y
Kanegae
A
A
Harada
T
T
Harada
D001407:Bacillus / Q000201:enzymology* / Q000378:metabolism; D004187:Disaccharides / Q000378:metabolism; D043326:Glucan 1,3-beta-Glucosidase; D005936:Glucans / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008970:Molecular Weight; D013379:Substrate Specificity; D047071:beta-Glucans; D001617:beta-Glucosidase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
D004187:Disaccharides; D005936:Glucans; D047071:beta-Glucans; C014637:laminaribiose; C038459:curdlan; D001617:beta-Glucosidase; D043326:Glucan 1,3-beta-Glucosidase