Treatment of ramie leaf β-amylase for preliminary purification

Abstract

The thermal properties of ramie leaf <TEX>${\beta}$</TEX>-amylase (RBA) were examined to develop a novel process for enzyme purification. The thermostability of RBA extract prepared from ramie leaf powder was examined at various temperatures. RBA activity decreased slightly, whereas other carbohydrate-active enzymes, such as <TEX>$\small{D}$</TEX>-enzyme, were rapidly inactivated during 30 min incubation at <TEX>$60^{\circ}C$</TEX>. When the heat-treated extract was incubated with various substrates, maltose was produced exclusively as the major product, whereas the untreated crude extract produced maltose and other maltooligosaccharides. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, fewer protein bands were observed for the heat-treated extract than the untreated extract, indicating that the thermostable RBA was partially purified and other thermolabile enzymes were eliminated. Thus, the treatment of the RBA extract at <TEX>$60^{\circ}C$</TEX> for 30 min resulted in 5.4-fold purification with a recovery yield of 90%.