Modulation of Cyclizing Activity and Thermostability of Cyclodextrin Glucanotransferase and Its Application as an Antistaling Enzyme

详细信息    查看全文

• 作者：Sung-Ho Lee ; Young-Wan Kim ; Suyong Lee ; Joong-Hyuck Auh ; Sung-Suk Yoo ; Tae-Jip Kim ; Jung-Wan Kim ; Sun-Tae Kim ; Hoe-Jin Rho ; Jin-Hwan Choi ; Young-Bae Kim ; and Kwan-Hwa Park
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2002
• 出版时间：March 13, 2002
• 年：2002
• 卷：50
• 期：6
• 页码：1411 - 1415
• 全文大小：80K
• 年卷期：v.50,no.6(March 13, 2002)
• ISSN：1520-5118

文摘

Cyclodextrin glucanotransferase from Bacillus stearothermophilus ET1 (CGTase ET1) is a potentialantistaling enzyme with cyclodextrin (CD)-forming activity. To reduce cyclization activity of CGTaseET1, phenylalanine residues at 191 and 255 were replaced with a glycine (F191G-CGTase ET1)and an isoleucine (F255I-CGTase ET1), respectively. Temperature optima of both mutant enzymeswere lower than that of the wild-type. Cyclization activities of both mutants decreased dramatically,but F255I-CGTase ET1 showed a 2-fold higher hydrolytic activity than the wild-type enzyme. CDcontent of bread loaf treated with F191G-CGTase ET1 was 28.6% of that treated with wild-type,whereas no CD was detected in the loaf treated with F255I-CGTase ET1. Loaves treated with CGTaseET1 or either of the two mutants contained more of the larger maltooligosaccharides such asmaltopentaose and maltohexaose than the control and the commercial antistaling enzyme-treatedloaves. Retrogradation rates decreased significantly in the loaves treated with either mutant, whichindicates the applicability of CGTase ET1 in the bread industry by modulating the cyclizing andhydrolyzing activities of the enzyme.Keywords: Cyclodextrin glucanotransferase (CGTase); retrogradation; antistaling enzyme; cyclization;site-directed mutagenesis