ヒト腸内細菌によるマルチトールの分解　ＩＩ　　Ｂｉｆｉｄｏｂａｃｔｅｒｉｕｍ　ａｄｏｌｅｓｃｅｎｔｉｓのマルチトール分解酵素（α‐グルコシダーゼ）の性質

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  • Some Characteristics of Maltitol-Hydrolyzing Enzyme (α-Glucosidase) from a Strain of <i>Bifidobacterium adolescentis</i>
  • Bifidobacterium adolescontis ノ マルチトール ブ

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Some enzymatic properties of three purified α-glucosidases (I, II a and II b) from the human intestinal bacterium, Bifidobacterium adolescentis type a, E 194 a were investigated. The optimal pH and temperature were pH 6.0 and 50°C for all three enzymes. The enzymes were all stable in a pH range from 5.5 to 8.0 (6°C, 24 hr) and retained activity up to 45°C, but at over 50°C (pH 6.0, 10min), they became inactivated in the order of enzyme I, II a and II b. The Km values for maltitol, maltose and phenyl α-glucoside were determined: for enzyme I, 3.2, 7.0 and 1.6×10-2M; for enzyme II a, 1.3, 6.0 and 0.22×10-2M; and for enzyme II b, 2.6, 11 and 0.29×10-2M, respectively. The degree of hydrolysis of maltitol by enzyme I, IIa and IIb (with respect to their maltase activity) was 100% at 6 hr, 55% at more than 15 hr, and about 2% at 27 hr, respectively. Enzyme I exhibited higher hydrolytic activity toward nigerose, kojibiose and maltitol in comparison with enzyme II a and II b, and no activity for sucrose and phenyl α-maltoside. Enzyme II a and II b both showed strong activity toward sucrose. All enzymes hydrolyzed phenyl α-glucoside remarkably. They showed activity toward dextrin alcohol, but no action was detected toward trehalose, soluble starch and β-glucoside. All three enzyme activities were inhibited strongly by Ag+, Hg2+, Cu2+, Zn2+, Cd2+ and Tris (hydroxymethyl) aminomethane, but no differences in inhibition were detected among the enzymes.

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