New alkalophilic β-galactosidase with high activity in alkaline pH region from Teratosphaeria acidotherma AIU BGA-1

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• 作者：Miwa Yamada^&Dagger ; ; Serina Chiba^&Dagger ; ; Yuta Endo ; Kimiyasu Isobe ; ^{kiso@iwate-u.ac.jp}
• 关键词：β-Galactosidase ; Lactase ; Alkalophilic lactase ; Teratosphaeria acidotherma ; Lactose
• 刊名：Journal of Bioscience and Bioengineering
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：123
• 期：1
• 页码：15-19
• 全文大小：527 K
• 卷排序：123

文摘

A β-d-galactosidase exhibiting high activity in the alkaline pH region was purified from Teratosphaeria acidotherma AIU BGA-1, which we previously isolated as a unique fungal producer of three acidophilic and one alkalophilic β-d-galactosidases (Isobe et al., J. Biosci. Bioeng., 116, 171–174, 2013). The enzyme was stable in the pH range 7.5–10.0 and exhibited optimal activity at pH 8.0 and 60°C. The enzyme hydrolyzed 2-nitrophenyl β-d-galactopyranoside, 4-nitrophenyl β-d-galactopyranoside, and lactose, and the Km values were estimated to be 0.349 mM, 0.488 mM, and 701 mM, respectively. Chelating reagents (EDTA and o-phenanthroline) and metals (Cu2+and Ni2+) inhibited the enzyme activity, and Mn2+ was a good activator. The enzyme also exhibited transgalactosylation activity for lactose. The enzyme's molecular mass was estimated to be 180 kDa, and its structure was monomeric. Thus, the enzymatic and physicochemical characteristics of the alkalophilic β-galactosidase in this study clearly differed from those of the previously known alkalophilic β-d-galactosidases.