Affinity purification of 4-alpha-glucanotransferase through formation of complex with insoluble amylose

Abstract

4-alpha-Glucanotransferases (alpha GTases) are useful enzymes to modify starch structure using their unique hydrolysis pattern and transglycosylation activity. In spite of lacking of a carbohydrate binding module, a thermostable aGTase from Thermus thermophilus (TT alpha GT) bound to insoluble amylose, leading to simple recovery of the enzyme-amylose complex using centrifugation. At a preparative scale, the recovery yield was 40.3% of the subjected free enzyme via collection of the complex twice. The complex exhibited improved thermostability, which shifted the optimum temperature from 70 to 80A degrees C and increased the half-life at 90A degrees C by three-fold compared with the free enzyme. Texture profile analysis of the gels made of modified starch by either free TT alpha GT or the complex revealed that the complex with double dosage showed the performance similar to free TT alpha GT in the modification of starch. In conclusion, the purification method described here would be useful due to easy scale-up and simple process without chromatographic process.