2006 Volume 53 Issue 4 Pages 273-275
An alkali-stable β-amylase was purified from Nagaimo, a cultivar of yam (Dioscorea opposita Thunb.) by hexadecyltrimethylammonium bromide treatment, ammonium sulfate fractionation, and two-step column chromatographic procedures on α-CD-Sepharose CL-4B and DEAE-Sephacel. Analysis by SDS-PAGE revealed the enzyme to be a monomeric protein with a 56 kDa molecular mass. This enzyme was stable for pH 4.0-12.0 at 4°C for 24 h. During two months, its activity remained about 40% at pH 9.5, but it fell below 20% at pH 5.0. Other properties such as optimum pH (5.6), and molecular mass resembled those of previously reported β-amylases. Thermal stability of this enzyme was not very high, either. From these results, this enzyme appears to be a good model for studying β-amylase stability.