Enzymatic synthesis of a beta-D-galactopyranosyl cyclic tetrasaccharide by beta-galactosidases.
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.
Higashiyama
Takanobu
T
Amase Institute, Hayashibara Biochemical Laboratories, Inc., 7-7 Amase Minami-machi, Okayama 700-0834, Japan. amaseken@hayashibara.co.jp
Watanabe
Hikaru
H
Aga
Hajime
H
Nishimoto
Tomoyuki
T
Kubota
Michio
M
Fukuda
Shigeharu
S
Kurimoto
Masashi
M
Tsujisaka
Yoshio
Y
D001236:Aspergillus oryzae / Q000201:enzymology; D001407:Bacillus / Q000201:enzymology; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002247:Carbon Isotopes; D002851:Chromatography, High Pressure Liquid; D005690:Galactose / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D007785:Lactose / Q000737:chemistry; D013058:Mass Spectrometry; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D002247:Carbon Isotopes; D001616:beta-Galactosidase; D007785:Lactose; D005690:Galactose