Characterization of raffinose synthase from rice (Oryza sativa L. var. Nipponbare).

The putative raffinose synthase gene from rice was cloned and expressed in Escherichia coli. The enzyme displayed an optimum activity at 45 degrees C and pH 7.0, and a sulfhydryl group was required for its activity. The enzyme was specific for galactinol and p-nitrophenyl-alpha-D-galactoside as galactosyl donors, and sucrose, lactose, 4-beta-galactobiose, N-acetyl-D-lactosamine, trehalose and lacto-N-biose were recognized as galactosyl acceptors.