文章基本信息

标题：THE EFFECTS OF MALTITOL ON RAT INTESTINAL DISACCHARIDASES
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作者：Setsuko YOSHIZAWA ; Sachiko MORIUCHI ; Norimasa HOSOYA 等
期刊名称：Journal of Nutritional Science and Vitaminology
印刷版ISSN：0301-4800
电子版ISSN：1881-7742
出版年度：1975
卷号：21
期号：1
页码：31-37
DOI：10.3177/jnsv.21.31
出版社：Center for Academic Publications Japan
摘要：1. The highest disaccharidase activity for sucrose, maltose and maltitol was found in the jejunum, followed by the ileum and duodenum. However, the disaccharidase activity for maltitol was extremely low compared with that for sucrose and maltose. 2. For maltitol, the K_m value was very large and the V _max value was very low compared with the values for sucrose and maltose. 3. The initial velocity ( v ) in the presence of sucrose and maltitol, was equal to the sum of the rates for individual substrates sucrose and maltitol ( v ₁, v ₂) respectively ( v = v ₁+ v ₂). Thus, no competition between these substrates was observed. In the case of maltose and maltitol, the initial velocity ( v ) in the presence of both substrates was less than the sum of the individual rates for maltose and maltitol ( v _l, v ₂) in the absence of the other substrate ( v < v _l+ v ₂). This finding demonstrates that there is competition between these two substrates for the same enzyme. Furthermore, the apparent Michaelis constant ( K_m ) and the apparent maximal velocity ( V _max) for pure and mixed substrates, i.e. , maltose and maltitol, at various mole fractions of maltose showed dependence on the mole fraction of maltose. The obtained kinetic data provide strong evidence that both maltose and maltitol react at the single active center of maltase.