Action of neopullulanase. Neopullulanase catalyzes both hydrolysis and transglycosylation at alpha-(1----4)- and alpha-(1----6)-glucosidic linkages.
Action of neopullulanase. Neopullulanase catalyzes both hydrolysis and transglycosylation at alpha-(1----4)- and alpha-(1----6)-glucosidic linkages.
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DOI：
10.1016/s0021-9258(19)36983-2
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发表时间：
1992-09
期刊：
影响因子：
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通讯作者：
H. Takata;T. Kuriki;S. Okada;Y. Takesada;M. Iizuka;N. Minamiura;T. Imanaka
中科院分区：
文献类型：
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作者：
H. Takata;T. Kuriki;S. Okada;Y. Takesada;M. Iizuka;N. Minamiura;T. Imanaka
对新支链淀粉酶催化的转糖基反应进行了分析。放射性低聚糖的产生时，酶作用于麦芽三糖在[U-14 C]葡萄糖的存在下。一些放射性寡糖仅具有α-（1- 4）-糖苷键，但其他放射性寡糖被认为具有α-（1- 6）-糖苷键。通过核磁共振氢谱和甲基化分析证实了麦芽三糖与新支链淀粉酶反应产物中存在α-（1- 6）-糖苷键。我们先前报道了新支链淀粉酶的一个活性中心催化α-（1- 4）-和α-（1- 6）-糖苷键的水解（Kuriki，T.，高田，H.，冈田，S.，和Imanaka，T.等人（1991）J. Bacteriol. 173，6147 -6152）。这些事实证明新支链淀粉酶催化所有四种类型的反应：α-（1- 4）-糖苷键水解、α-（1- 6）-糖苷键水解、转糖基化形成α-（1- 4）-糖苷键和转糖基化形成α-（1- 6）-糖苷键。这四种反应通常分别由α-淀粉酶、支链淀粉酶、环麦芽糖糊精葡聚糖转移酶和1，4-α-D-葡聚糖分支酶催化。这四种酶彼此具有一些结构相似性，但这些酶催化的反应被认为是独特的：这四种反应分别由每种酶催化。对新支链淀粉酶的反应分析表明，这四种反应的催化机理是一致的。
The transglycosylation reaction catalyzed by neopullulanase was analyzed. Radioactive oligosaccharides were produced when the enzyme acted on maltotriose in the presence of [U-14C]glucose. Some of the radioactive oligosaccharides had only alpha-(1—-4)-glucosidic linkages, but others were suggested to have alpha-(1—-6)-glucosidic linkages. The existence of alpha-(1—-6)-glucosidic linkages in the products from maltotriose with neopullulanase was proven by proton NMR spectroscopy and methylation analysis. We previously reported that the one active center of neopullulanase catalyzes the hydrolysis of alpha-(1—-4)- and alpha-(1—-6)-glucosidic linkages (Kuriki, T., Takata, H., Okada, S., and Imanaka, T. (1991) J. Bacteriol. 173,6147-6152). These facts proved that neopullulanase catalyzed all four types of reactions: hydrolysis of alpha-(1—-4)-glucosidic linkage, hydrolysis of alpha-(1—-6)-glucosidic linkage, transglycosylation to form alpha-(1—-4)-glucosidic linkage, and transglycosylation to form alpha-(1—-6)-glucosidic linkage. The four reactions are typically catalyzed by alpha-amylase, pullulanase, cyclomaltodextrin glucanotransferase, and 1,4-alpha-D-glucan branching enzyme, respectively. These four enzymes have some structural similarities to one other, but reactions catalyzed by the enzymes are considered to be distinctive: the four reactions are individually catalyzed by each of the enzymes. The experimental results obtained from the analysis of the reaction of the neopullulanase exhibited that the four reactions can be catalyzed in the same mechanism.