Higashiyama Takanobu, Watanabe Hikaru, Aga Hajime, Nishimoto Tomoyuki, Kubota Michio, Fukuda Shigeharu, Kurimoto Masashi, Tsujisaka Yoshio
Amase Institute, Hayashibara Biochemical Laboratories, Inc., 7-7 Amase Minami-machi, Okayama 700-0834, Japan.
Carbohydr Res. 2004 Jun 22;339(9):1603-8. doi: 10.1016/j.carres.2004.04.005.
The galactosyl transfer reaction to cyclo-[-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->] (CTS) was examined using lactose as a donor and beta-galactosidases from Aspergillus oryzae and Bacillus circulans. The A. oryzae beta-galactosidase produced three galactosyl derivatives of CTS. The main galactosyl derivative produced by the A. oryzae enzyme was identified as 6-O-beta-D-galactopyranosyl-CTS, cyclo-[-->6)-alpha-D-Glcp-(1-->3)-[beta-D-Galp-(1-->6)]-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->]. The B. circulans beta-galactosidase also synthesized three galactosyl-transfer products to CTS. The structure of main transgalactosylation product was 3-O-beta-D-galactopyranosyl-CTS, cyclo-[-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-[beta-D-Galp-(1-->3)]-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->]. These results showed that beta-galactosidase transferred galactose directly to the ring glucose residue of CTS.
以乳糖为供体，利用米曲霉和环状芽孢杆菌的β-半乳糖苷酶，研究了对半乳糖基转移反应至环-[→6)-α-D-葡萄糖-(1→3)-α-D-葡萄糖-(1→6)-α-D-葡萄糖-(1→3)-α-D-葡萄糖-(1→]（CTS）的情况。米曲霉β-半乳糖苷酶产生了CTS的三种半乳糖基衍生物。米曲霉酶产生的主要半乳糖基衍生物被鉴定为6-O-β-D-吡喃半乳糖基-CTS，即环-[→6)-α-D-葡萄糖-(1→3)-[β-D-半乳糖-(1→6)]-α-D-葡萄糖-(1→6)-α-D-葡萄糖-(1→3)-α-D-葡萄糖-(1→]。环状芽孢杆菌β-半乳糖苷酶也合成了三种CTS的半乳糖基转移产物。主要转半乳糖基化产物的结构为3-O-β-D-吡喃半乳糖基-CTS，即环-[→6)-α-D-葡萄糖-(1→3)-α-D-葡萄糖-(1→6)-[β-D-半乳糖-(1→3)]-α-D-葡萄糖-(1→3)-α-D-葡萄糖-(1→]。这些结果表明，β-半乳糖苷酶可将半乳糖直接转移至CTS的环葡萄糖残基上。
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