ISOLATION OF ALPHA-AMYLASE ON CROSS-LINKED STARCH

The isolation and purification of alpha-amylase from an industrial enz yme sample is described using crosslinked starch powder as an affinity adsorbent. The process was studied with regard to the stability of th e adsorbent, the stability of the enzyme, and the capacity of the adso rbent for the enzyme. The adsorbent was used in a repented adsorption- desorption process to evaluate the binding capacity and stability of t he 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 ads orption levels up to 0.5 mg protein per mg adsorbent. The matrix itsel f was slowly degraded, but no decline of the adsorption levels was obs erved during 90 cycles under the experimental conditions used. The lif etime of the matrix was estimated to be 140 repeated runs. Approximate ly 10-40 kg of pure alpha-amylase can be obtained with 1 kg of adsorbe nt. This may yield an economically attractive purification process bec ause the adsorbent is cheap and easy to prepare, as it consists of sta rch crosslinked with epichlorohydrin.