Y. Suzuki et al., PURIFICATION AND CHARACTERIZATION OF AN OLIGO-1,6-GLUCOSIDASE FROM THE CALDOACTIVE THERMOPHILE BACILLUS-CALDOTENAX, Starke, 49(4), 1997, pp. 148-154
An oligo-1,6-glucosidase (dextrin 6-alpha-D-glucanhydrolase, EC 3.2.1.
10) of the caldoactive thermophile Bacillus caldotenax KP1213 (YT-G, D
SM406) was purified to homogeneity. Its relative molecular weight, Sto
kes radius, sedimentation coefficient at 20 degrees C in water, molar
absorption coefficient at 280 nm and pH 6.8, and isoelectric point wer
e estimated to be 64,000, 3.3 nm, 4.8S, 122,000 M-1 cm(-1), and 4.9, r
espectively. The enzyme N-terminal sequence of twenty residues was det
ermined to be a-Val-Val-Tyr-Gln-Ile-Tyr-Pro-Arg-Met-Phe-Tyr(20). The e
nzyme shared its antigenic groups in part with the homologue from Baci
llus thermoglucosidastus KP1006 (DSM2542, obligate thermophile). The B
, caldotenax enzyme was most active at 70 degrees C and at pH 6.0-6.8.
The best substrate for the enzyme was isomaltotriose of naturally-occ
urring oligo-and polysaccharides tested. The enzyme half-life at pH 6.
5 was 10 min at 75 degrees C. The enzyme (Pro, 5.93mol%) fairly matche
d with a positive relationship between the thermostability of its six
bacillary counterparts and their proline mol% contents. This relations
hip has been found to hold for sixteen bacterial enzymes from other fo
ur different groups (alpha-glucosidases, pullulanases and 3-isopropylm
alate dehydrogenases).