alpha-Galactosidases catalyze the hydrolysis of alpha-1,6-linked galactosyl residues from galacto-oligosaccharides and polymeric galacto-(gluco)mannans. The crystal structure of rice alpha-galactosidase has been determined at 1.5A resolution using the multiple isomorphous replacement method ...
alpha-Galactosidases catalyze the hydrolysis of alpha-1,6-linked galactosyl residues from galacto-oligosaccharides and polymeric galacto-(gluco)mannans. The crystal structure of rice alpha-galactosidase has been determined at 1.5A resolution using the multiple isomorphous replacement method. The structure consisted of a catalytic domain and a C-terminal domain and was essentially the same as that of alpha-N-acetylgalactosaminidase, which is the same member of glycosyl hydrolase family 27. The catalytic domain had a (beta/alpha)8-barrel structure, and the C-terminal domain was made up of eight beta-strands containing a Greek key motif. The structure was solved as a complex with d-galactose, providing a mode of substrate binding in detail. The d-galactose molecule was found bound in the active site pocket on the C-terminal side of the central beta-barrel of the catalytic domain. The d-galactose molecule consisted of a mixture of two anomers present in a ratio equal to their natural abundance. Structural comparisons of rice alpha-galactosidase with chicken alpha-N-acetylgalactosaminidase provided further understanding of the substrate recognition mechanism in these enzymes.
Related Citations:
Crystallization and preliminary X-ray crystallographic studies of rice alpha-galactosidase Fujimoto, Z., Kobayashi, O., Kaneko, S., Momma, M., Kobayashi, H., Mizuno, H. (2002) Acta Crystallogr D Biol Crystallogr 58: 1374
alpha-Galactosidase from cultured rice (Oryza sativa L. var. Nipponbare) cells Kim, W., Kobayashi, O., Kaneko, S., Sakakibara, Y., Park, G., Kusakabe, I., Tanaka, H., Kobayashi, H. (2002) Phytochemistry 61: 621
Organizational Affiliation:
Department of Biochemistry, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
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