Characterization of recombinant β-amylases from Oryza sativa.

Four putative β-amylase genes found in the Oryza sativa cDNA sequence database (KOME) were expressed in Escherichia coli. Recombinant proteins from two of these genes showed β-amylase activity. Similarly to β-amylases from other plants, the optimum pH of the recombinant rice β-amylases was about 5.5-6.0, but they exhibited inferior heat stability to soybean β-amylase.