PURIFICATION AND CHARACTERIZATION OF CYCLODEXTRIN GLYCOSYLTRANSFERASEFROM PAENIBACILLUS SP. F8

Cyclodextrin glycosyltransferases (E.C. 2.4.1.19) (CGTases) are indust rially important enzymes for the production of cyclodextrins (CD) from starch. While cyclomaltohexaose (alpha-CD), cyclomaltoheptaose (beta- CD), and cyclomaltooctaose (gamma-CD) are the most commonly reported p roducts, the production of cyclomaltononaose (delta-CD) by CGTases has not been studied previously. A CGTase from Paenibacillus sp. F8 was p urified and characterised. The molecular weight was estimated to be 72 kDa by SDS-PAGE. The pH optima of the enzyme were 7.5 for the cyclisa tion activity and 8.0 for the hydrolysis activity. The temperature opt ima for the cyclisation and hydrolysis activities were 50 and 60 degre es C, respectively. Ca++ had a stabilising effect on the enzyme activi ty. The initial production ratio of alpha-CD, beta-CD, gamma-CD, and d elta-CD from soluble starch was 0.09:1:0.25.0.14. Prolonged incubation times resulted in a decreased ratio of delta-CD and, to a lesser exte nt, of gamma-CD and a increased ratio of alpha- and beta-CD compared t o the other CD. Coupling experiments showed that delta-CD was more eas ily degraded by Paenibacillus sp. F8 CGTase compared to alpha-, beta-, and gamma-CD. (C) 1998 Elsevier Science Ltd. All rights reserved.