Purification, Properties, and N-Terminal Amino Acid Sequences of Guar Gum-degrading Enzyme from Bacillus circulans K-1

抄録

A guar gum-degrading enzyme of the newly isolated Bacillus circulans K-1 was purified to an electrophoretically homogeneous state. The molecular weight of the purified enzyme was 62, 000 by SDS-PAGE. The purified enzyme was separated into at least six isozymes by isoelectric focusing and the pI of these isozymes were 5.4, 5.5, 5.6, 5.8, 6.0, and 6.2, respectively. The N-terminal amino acid sequences of the typical three of these proteins were all the same, Ala-Ser-Gly-Phe-Tyr-Val-Ser-Gly-Thr-Lys-Leu-Leu-Asp-Ala-Thr-Gly-Gln-Pro-Phe-Val-Met-Arg. The enzyme was most active at pH 6.9 and at 64°C. The enzyme was activated slightly by Al³⁺ and inhibited strongly by Sn²⁺ and Zn²⁺, N-bromosuccinimide, 2-mer-captoethanol, and ethylenediamine-tetraacetic acid.