An Acidophilic β-Galactosidase from Bispora sp. MEY-1 with High Lactose Hydrolytic Activity under Simulated Gastric Conditions

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• 作者：Hui Wang ; Huiying Luo ; Yingguo Bai ; Yaru Wang ; Peilong Yang ; Pengjun Shi ; Wei Zhang ; Yunliu Fan ; Bin Yao
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2009
• 出版时间：June 24, 2009
• 年：2009
• 卷：57
• 期：12
• 页码：5535-5541
• 全文大小：928K
• 年卷期：v.57,no.12(June 24, 2009)
• ISSN：1520-5118

文摘

BgalA, a full-length gene (3,009 bp) that encodes a β-galactosidase, was cloned from the meso-acidophilic fungus Bispora sp. MEY-1 and expressed in Pichia pastoris. The deduced amino acid sequence of BgalA shares highest identity (55.5%) with the β-galactosidase from Aspergillus phoenicis, which belongs to the glycoside hydrolyase family 35. Purified recombinant BgalA is acidophilic, exhibiting maximum activity at pH 1.5, which is lower than that reported for other β-galactosidases. The enzyme has high pH and thermal stability and is resistant to proteases and cations found in milk. The K_m and V_max of BgalA for 2-nitrophenyl-β-d-galactopyranoside and lactose are 5.22 mM and 120.8 μmol/(min·mg), and 0.31 mM and 137.3 μmol/(min·mg), respectively. Under simulated gastric conditions, BgalA has greater stability (100%) and hydrolysis ratio (>80%) toward milk lactose than the commercially available β-galactosidase from Aspergillus oryzae (ATCC 20423). Thus, BgalA may be a better digestive supplement for alleviating symptoms associated with lactase deficiency.