Affinity Binding of Higher Plant β‐Amylases to Starch. A Rapid Purification Method

A rapid purification method exploiting affinity of higher plant β‐amylases to its substrate starch is described. Mustard β‐amylase on incubation with starch suspension binds rapidly to starch. The enzyme binds tenaciously to starch as various eluants as concentrated salt solutions, α‐cyclodextrin and shift in elution pH could not significantly elute the bound enzyme. Even maltose only partially eluted the bound enzyme at high concentrations (5% w/v) after a prolonged incubation time (24 h). Nevertheless, the enzyme could be rapidly eluted from starch with white dextrin (1% w/v). The eluted enzyme fractions consisted of β‐amylase purified to homogeneity. The above starch‐affinity purification process could also be applied to other higher plant β‐amylases such as sweet potato and barley.