Debranching Enzymes of Potato Tubers (Solanum tuberosum L.). I. Purification and Some Properties of Potato Isoamylase
Debranching Enzymes of Potato Tubers (Solanum tuberosum L.). I. Purification and Some Properties of Potato Isoamylase
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马铃薯块茎（Solanum tuberosum L.）的脱支酶。
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
Michinori Nakamura
中科院分区：
文献类型：
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作者：
Y. Ishizaki;H. Taniguchi;Y. Maruyama;Michinori Nakamura
马铃薯块茎含有3种脱支酶，可通过聚丙烯酰胺凝胶电泳分离。其中异淀粉酶经过等电沉淀、硫酸铵分馏、Sepharose 6B凝胶过滤、Sepharose 4b可溶性淀粉亲和层析等步骤，在圆盘凝胶电泳上得到了明显的均匀性。纯化酶的比活性为8.0U/mg蛋白质。它对糖原和植物糖原中的α- 1,6 -糖苷键的水解速度与支链淀粉一样快且完全，但不能水解普鲁兰。结果表明，马铃薯异淀粉酶与假单胞菌异淀粉酶具有相同的底物特异性。但与后者不同的是，它的最适pH为5.5 ~ 6.0，最适温度为50℃，并能被对苯甲酸氯汞可逆灭活。
Potato tubers contain 3 debranching enzymes separable by polyacrylamide gel electrophoresis. One of them, isoamylase, has been purified to apparent homogeneity on disc gel electrophoresis by isoelectric precipitation, fractionation with ammonium sulfate, gel filtration on Sepharose 6B and finally affinity chromatography on Sepharose 4B-soluble starch, successively. The purified enzyme has a specific activity of 8.0U/mg of protein. It hydrolyzes the α-l,6-glucosidic bonds in glycogen and phytoglycogen not only as rapidly as those in amylopectin but also completely, but cannot hydrolyze pullulan. From these results potato isoamylase was found to have the same substrate specificity as that of Pseudomonas isoamylase. However, different from the latter, it has an optimum pH of 5.5 ~ 6.0, optimum temperature of 50°C and was reversibly inactivated by p-chloromercuri- benzoate.