Characterization of a Thermostable Cyclodextrin Glucanotransferase Isolated from Bacillus stearothermophilus ET1

Abstract

A thermostable cyclodextrin glucanotransferase (CGTase) was isolated from a Bacillus stearothermophilus strain, ET1, which was screened from Korean soil. The corresponding CGTase gene cloned in Escherichia coli shared 84% and 88% identity with CGTase genes from other B. stearothermophilus strains at the nucleotide and amino acid sequence level, respectively. The enzyme was purified to apparent homogeneity by β-cyclodextrin (CD) affinity chromatography and high-performance liquid chromatography. The enzyme had an apparent molecular mass of 66,800 Da and a pI of 5.0. The optimum pH for the enzyme-catalyzed reaction was pH 6.0, and the optimum temperature was observed at 80 °C. Thermostability of the enzyme was enhanced by Ca2+. A 13% (w/v) cornstarch solution was liquefied and converted to CDs solely using this enzyme. The cornstarch conversion rate was 44% and α-, β-, and γ-CDs were produced in the ratio of 4.2:5.9:1. Keywords: Cyclodextrin glucanotransferase; thermostability; cyclodextrin; Bacillus stearothermophilus

Characterisation of cyclodextrin glucanotransferase fromBacillus circulans ATCC 21783 in terms of cyclodextrin production

“…As separation of different CDs is costly and timeconsuming, CGTase that synthesizes predominantly one type of CD is of interest. Generally, the majority of the Bacillus CGTases convert starch into β-CD as the main product (Sabioni and Park, 1992;Marechal et al, 1996;Chung et al, 1998;Gawande et al, 1999;Park et al, 1999;Martins and Hatti-Kaul, 2002;Sian et al, 2005). The ability of CDs to form inclusion complexes with many organic and inorganic molecules, changing their physical and chemical properties makes CGTase an important enzyme for the medicine, food, cosmetic, pharmaceutical industries and in environmental protection (Szejtli, 1997;Singh et al, 2002).…”

Improved activity of β-cyclodextrin glycosyltransferase from Bacillus sp. N-227 via mutagenesis of the conserved residues

“…When aspartic acid 229 nucleophilic attack C1 as shown in Fig. 6, the carboxyl ionization, the arginine with positive charge took the place of the negatively charged aspartic acid 355, the existence of positive charge was more advantageous to ASP229 nucleophilic attack C1, and conducive to Asp229 nucleophilic attack C1, and conducive to the substrate cyclization (Chung et al 1998;Kragh et al 2010).…”

“…Extreme pH values were not suitable for the enzyme to carry out cyclization activity. Most of the reported CGTases exhibited optimum pH range from 5.0 to 8.0 (Bovetto et al 1992;Chung et al 1998;Tachibana et al 1999;Sian et al 2005), but the enzyme from Brevi-bacterium sp. no.…”

Aplicação de xilanase e/ou ciclodextria glicotransferase (CGTase) na produção de pães

“…Alguns pesquisadores relacionam a firmeza do miolo com as transformações que ocorrem no amido, principalmente a formação de estruturas em dupla hélice e aumento das regiões cristalinas (ZOBEL; , e mais recentemente a utilização de enzimas têm se destacado como um caminho promissor para a melhoria da qualidade de produtos panificáveis. Entre as enzimas amplamente estudadas que alteram as propriedades do amido ou dos polissacarídeos não amiláceos, para melhorar as características da massa melhorando a qualidade dos pães e minimizando os efeitos do processo de envelhecimento destacam-se as α-amilases (Defloor;, xilanases e as CGTases Chung et al, 1998).…”

“…Essa enzima é capaz de hidrolisar o amido em uma série de dextrinas cíclicas não-reduzidas contendo seis (α), sete (β) e oito (γ) unidades de glicose, respectivamente, que são unidas por ligações glicosídicas α-(1,4), além da produção de dextrinas de baixo peso molecular . Há relatos na literatura de que uma CGTase termoestável isolada de Bacillus stearothermophilus ET1 (CGTase ET1) produz vários maltooligossacarídeos que atuam como potente agente antienvelhecimento no pão (CHUNG et al, 1998). Também foi relatado que o volume do pão aumentou devido à ação de dextrinas produzidas pela CGTase adicionada à massa do pão .…”