A protease-resistant exo-polygalacturonase from Klebsiella sp. Y1 with good activity and stability over a wide pH range in the digestive tract
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- 作者：Peng Yuan ; Kun Meng ; Yaru Wang ; Huiying Luo ; Pengjun Shi ; Huoqing Huang ; Yingguo Bai ; Peilong Yang ; Bin Yao
- 关键词：Exo-polygalacturonase ; Klebsiella sp ; Feed and food additive ; PF00295 family
- 刊名：Bioresource Technology
- 出版年：2012
- 出版时间：November, 2012
- 年：2012
- 卷：123
- 期：Complete
- 页码：171-176
- 全文大小：530 K
文摘
Polygalacturonases are important feed and food additives. In the present study an exo-polygalacturonase gene (pgu B) was cloned from Klebsiella sp. Y1 CGMCC 4433 and expressed in Escherichia coli BL21 (DE3). pgu B encodes a 658-amino acid polypeptide belonging to Glycoside Hydrolase Family 28. The optimal pH and temperature of exo-PGU B activity were 6.0 and 40-50 ¡ãC, respectively. The enzyme exhibited >35 % of maximum activity within the pH range of 2.0-12.0. Exo-PGU B or an exo-PGU B/ endo-polygalacturonase mixture reduced the viscosity of polygalacturonic acid (1.0 % , w/v) by 15.6 and 39.4 % , respectively. Under simulated alimentary tract conditions, exo-PGU B was very stable (>25 % activity from pH 1.5 to 6.8) and active, releasing 53.7 and 109.6 ¦Ìg of galacturonic acid from 400 to 800 ¦Ìg of polygalacturonic acid, respectively. These properties make exo-PGU B a potentially valuable additive for applications in feed and food.