Shim Jae-Hoon, Seo Nam-Seok, Roh Sun-Ah, Kim Jung-Wan, Cha Hyunju, Park Kwan-Hwa
Center for Agricultural Biomaterials, School of Agricultural Biotechnology, Seoul National University, Shillim-dong, Kwanak-gu, Seoul 151-742, Korea.
J Agric Food Chem. 2007 Jun 13;55(12):4735-40. doi: 10.1021/jf070217d. Epub 2007 May 9.
A bread-baking process was developed using a potential novel enzyme, cyclodextrin glucanotransferase[3-18] (CGTase[3-18]), that had previously been engineered to have enhanced hydrolyzing activity with little cyclodextrin (CD) formation activity toward starch. CGTase[3-18] was primarily manipulated to be displayed on the cell surface of Saccharomyces cerevisiae. S. cerevisiae carrying pdeltaCGT integrated into the chromosome exhibited starch-hydrolyzing activity at the same optimal pH and temperature as the free enzyme. Volumes of the bread loaves and rice cakes prepared using S. cerevisiae/pdeltaCGT increased by 20% and 45%, respectively, with no detectable CD. Retrogradation rates of the bread and rice cakes decreased significantly during storage. In comparison to the wild type, S. cerevisiae/pdeltaCGT showed improved viability during four freeze-thaw cycles. The results indicated that CGTase[3-18] displayed on the surface of yeast hydrolyzed starch to glucose and maltose that can be used more efficiently for yeast fermentation. Therefore, display of an antistaling enzyme on the cell surface of yeast has potential for enhancing the baking process.
利用一种潜在的新型酶——环糊精葡糖基转移酶[3-18]（CGTase[3-18]）开发了一种面包烘焙工艺，该酶此前经过改造，具有增强的水解活性，对淀粉形成环糊精（CD）的活性较低。CGTase[3-18]主要被操控以展示在酿酒酵母的细胞表面。携带整合到染色体中的pdeltaCGT的酿酒酵母在与游离酶相同的最佳pH和温度下表现出淀粉水解活性。使用酿酒酵母/pdeltaCGT制备的面包和米糕的体积分别增加了20%和45%，且未检测到CD。面包和米糕在储存期间的回生率显著降低。与野生型相比，酿酒酵母/pdeltaCGT在四个冻融循环中显示出更高的活力。结果表明，展示在酵母表面的CGTase[3-18]将淀粉水解为葡萄糖和麦芽糖，可更有效地用于酵母发酵。因此，在酵母细胞表面展示一种抗老化酶具有增强烘焙过程的潜力。
