Purification and characterization of Bacillus coagulans oligo-1,6-glucosidase

A p-nitrophenyl-alpha-D-glucopyranoside-hydrolyzing oligo-1,6-glucosidase of Bacillus coagulans ATCC 7050 (facultative thermophile) was purified to homogeneity. The relative molecular mass, Stokes radius, sedimentation coefficient at 20 degrees C in water, molecular absorption coefficient at 280 nm and pH 6.8, and isoelectric point were estimated as 60 000, 3.29 nm, 4.8 X 10(-13) s, 1.34 X 10(5) M-1 cm-1, and 4.3, respectively. The amino-terminal amino acid was threonine. There was no common antigenic group between the enzyme and each of its homologous counterparts from Bacillus cereus ATCC 7064 (mesophile) and Bacillus thermoglucosidasius KP 1006 (obligate thermophile). These oligo-1,6-glucosidases strongly resembled one another in their amino acid composition, except that the proline content increased with the elevation of thermostability in the order, mesophile----facultative thermophile----obligate thermophile enzymes.