SUBSTRATE-SPECIFICITY OF MAIZE BETA-GLUCOSIDASE
SUBSTRATE-SPECIFICITY OF MAIZE BETA-GLUCOSIDASE
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DOI：
10.1016/0168-9452(94)90162-7
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发表时间：
1994-01-01
期刊：
影响因子：
5.2
通讯作者：
ESEN, A
中科院分区：
文献类型：
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作者：
BABCOCK, GD;ESEN, A
玉米(Zea Mays L.)β-葡萄糖苷酶(β-Glu)是一种60 kDa的同源二聚体，定位于叶绿体中。以多种糖苷为底物进行了试验。尽可能测定K-m和V-max。玉米幼苗甲醇提取物中的主要天然底物是2，4-dihydroxy-7-methoxy-2H-1，4-benzoxazin-3(4H)-one的糖苷(DIMBOA-GLC)，该物质在酶的作用下被降解为葡萄糖和DIMBOA。4-甲基伞形花环-β-D-葡萄糖苷是最好的底物(K-m=0.14 mm)，获得了动力学数据。几种芳基糖苷(K-m=0.39-6.32 mM)和正辛基-β-D-吡喃葡萄糖苷也是底物。各种化合物也被作为抑制剂进行了测试。当观察到抑制时，估计K-I和/或K-I‘值。单糖是较差的抑制物。最好的竞争性抑制剂是D-葡萄糖酸内酯、熊果苷和DIMBOA(K-I值
Maize (Zea mays L.) beta-glucosidase (beta-glu) is a homodimer of 60-kDa monomers and localized in the plastid. Numerous glycosides were tested as substrates. When possible, K-m and V-max values were determined. The major natural substrate in methanol extracts of young maize seedlings was the glucoside of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA-glc) and this substance was hydrolyzed to glucose and DIMBOA by the enzyme. 4-Methylumbelliferyl-beta-D-glucoside was the best substrate (K-m = 0.14 mM) for which kinetic data were obtained. Several aryl glycosides (K-m = 0.39-6.32 mM) and n-octyl-beta-D-glucopyranosides were also substrates. Various compounds were also tested as inhibitors. When inhibition was observed, K-i and/or K-i' values were estimated. Monosaccharides were poor inhibitors. The best competitive inhibitors were D-gluconic acid lactone, dhurrin, and (DIMBOA) (K-i values