Isolation of α-amylase on crosslinked starch

The isolation and purification of α-amylase from an industrial enzyme sample is described using crosslinked starch powder as an affinity adsorbent. The process was studied with regard to the stability of the adsorbent, the stability of the enzyme, and the capacity of the adsorbent for the enzyme. The adsorbent was used in a repeated adsorption-desorption process to evaluate the binding capacity and stability of the adsorbents in continuous processes. The adsorption kinetics of the matrix was improved because during the repeated process the diffusion resistance of the matrix decreased. This effect was accompanied by an increase of the capacity of the adsorbent for the enzyme, yielding adsorption levels up to 0.5 mg protein per mg adsorbent. The matrix itself was slowly degraded, but no decline of the adsorption levels was observed during 90 cycles under the experimental conditions used. The lifetime of the matrix was estimated to be 140 repeated runs. Approximately 10–40 kg of pure α-amylase can be obtained with 1 kg of adsorbent. This may yield an economically attractive purification process because the adsorbent is cheap and easy to prepare, as it consists of starch crosslinked with epichlorohydrin.