Isolation and characterization of cyclodextrin glycosyltransferase isozymes from Bacillus sp. A11

Abstract

Cyclodextrin glycosyltransferase isozymes form Bacillus sp.A11 were purified by preparative gel electrophoresis. Four isozymes (bands 1, 2, 3, and 4 ) were separated by this technique with purification factor up to 211 tolds. Their isoelectric points were estimated by isoelectrocusing gel to be 4.73, 4.49 , 4.40 and 4.31, respectively . Their molecular weights on sodium dodecyl sulfate-gel electrophoresis were 72,000 daltonsm They were proved to be glycoproteins by Periodic acid-Shiff’s staining on native-gel electrophoresis. Their carbohydrate contents were determined by phenol-sulfuric acid method to be 20.5 , 18.7, 14.4 and 46.7% (w/w). respectively. Some physical and biochemical properties were analyzed. Their pH optima wrer 6.0-7.0 , 6.0 -7.0, 6.0 and 7.0 , terperature optima were 40℃, 40℃ ,50℃ และ 50-60℃ and the ratio of α- , β- and y-cyclodextrins produced were determined as 10:18:5, 9:18:5, 5:18:5 and 5:18:7 for bands 1, 2, 3, and 4 respectively. Moreover, distinct linear oligosaccharide products were observed, The result obtained indicated that these 4 isozymes may be catalyitically different. Study on their amino acid compositions showed significant difference on the content of glutamine, histidine, alanine, praline and tyrosine.