Purification and Characterization of Cyclodextrin Glucanotransferase from Paenibacillus sp. JK-12

Abstract

Extracellular cyclodextrin glucanotransferase (CGTase) from Paenibacillus sp. JK-12 was purified through several purification steps consisting of ammonium sulfate precipitation and chromatographies on DEAE-sephadex A-50 and Mono QIM HR5/5. The purified CGTase exhibited a single band on SDS-PAGE and was estimated to be approximately 82 kDa. The isoelectric point of the enzyme was 7.2 as determined by isoelectric focusing. The CGTase from Paenibacillus sp. JK-12 had a transglucosylation activity at the C-2 position of L-ascorbic acid. The optimum pH and temperature for the CGTase activity were 8.0 and 50oC, respectively. The enzyme activity was stable from pH 6.0 to 9.0 and at temperatures up to 55℃ at pH 8.0, having 80% residual activity. The activity of the CGTase was strongly resistant to metals such as Ag^+ and Ba^(2+) but slightly inhibited by Hg^+, Ni^(2+) and Mg^(2+). The enzymeproducedα-cyclodextrin (α-CD) and β-CD as the main products from starch, but not γ-CD.