ISOLATION OF STARCH BRANCHING ENZYME-I FROM POTATO USING GAMMA-CYCLODEXTRIN AFFINITY-CHROMATOGRAPHY

This study presents a novel, fast and easy method to isolate starch br anching enzyme I (EC 2.4.1.18, SEE-I) from potato (Solanum tuberosum L . cv. 'Dianella') by gamma-cyclodextrin (gamma-CD) affinity chromatogr aphy of the supernatant obtained after polyethylene glycol 6000 precip itation of the crude homogenate. SBE-I was specifically eluted by comp etition with free gamma-CD. The resulting protein fraction was homogen eous, as analysed by sodium dodecyl sulphate-polyacrylamide gel electr ophoresis and contained no contaminating hydrolytic activities, as mon itored by activity staining using zymograms and specific assays for al pha- and beta-amylase. The overall purification was 296-fold and the y ield was 38%. (C) 1998 Elsevier Science B.V.