The interaction of 1-fluoro-D-glucopyranosyl fluoride with glucosidases.
The interaction of 1-fluoro-D-glucopyranosyl fluoride with glucosidases.
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1-氟-D-吡喃葡萄糖基氟化物与葡萄糖苷酶的相互作用。
DOI：
10.1042/bj2790587
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Sinnott,ML
中科院分区：
文献类型：
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作者：
Konstantinidis,A;Sinnott,ML
1. 1-氟-D-吡喃葡萄糖基氟化物在50.0 ℃下以1 × 10（-8）s-1的速率经历F-离子的pH非依赖性损失，比α-D-吡喃葡萄糖基氟化物慢约10（3）倍，比β-D-吡喃葡萄糖基氟化物慢4 × 10（4）倍。2.尼日尔曲霉的（转化）淀粉葡糖苷酶II根据Michaelis-Menten动力学（Km 34 mM和kcat. 0.27 s-1），通过与其水解α-D-吡喃葡萄糖基氟化物（Km 38 mM和kcat. 730 s-1），而不是通过用于转化β-D-吡喃葡萄糖基氟化物的Hehre再合成-水解机制。3.二氟化物也是猪肾（转化）海藻糖酶的底物[Km 17.3 mM和Vmax。6.2 x 10（-4），相对于α-D-吡喃葡萄糖基氟化物（Km 38 mM）。4.氟取代的一步酶促反应和非酶促反应的定量相似的效果表明，它们通过类似的（氧碳离子样）过渡态。5.二氟化物是来自文氏曲霉（Aspergillus wentii）（A3酶）和甜杏仁粉（B同工酶）的（保留的）β-葡糖苷酶以及来自大米的保留的α-葡糖苷酶的底物：与适当的一氟化物的比较揭示了第二个氟原子对kcat的可变速率延迟效应。Km与过渡态氧碳正离子特征的其他测量值相关。6.二氟化物是来自酵母的（保留）α-葡糖苷酶的底物，但也对活性位点定向的不可逆抑制产生了潜在的模仿，我们暂时将其归因于非共价复合物的形成或氟葡萄糖基-酶增加了这种酶通过吸附在容器壁上而从溶液中出来的众所周知的趋势。
1. 1-Fluoro-D-glucopyranosyl fluoride undergoes pH-independent loss of F- ion at a rate of 1 x 10(-8) s-1 at 50.0 degrees C, some 10(3)-fold slower than alpha-D-glucopyranosyl fluoride and 4 x 10(4)-fold slower than beta-D-glucopyranosyl fluoride. 2. The (inverting) amyloglucosidase II of Aspergillus niger hydrolyses the difluoride according to Michaelis-Menten kinetics (Km 34 mM and kcat. 0.27 s-1), by apparently the same (simple) mechanism by which it hydrolyses alpha-D-glucopyranosyl fluoride (Km 38 mM and kcat. 730 s-1), rather than by the Hehre resynthesis-hydrolysis mechanism used to transform beta-D-glucopyranosyl fluoride. 3. The difluoride is also a substrate for the (inverting) trehalase of pig kidney [Km 17.3 mM and Vmax. 6.2 x 10(-4) relative to alpha-D-glucopyranosyl fluoride (Km 38 mM]). 4. The quantitatively similar effect of fluorine substitution on the one-step enzymic reactions and on the non-enzymic reactions suggests that they go through similar (oxocarbonium-ion-like) transition states. 5. The difluoride is a substrate for the (retaining) beta-glucosidases from Aspergillus wentii (A3 enzyme) and sweet-almond meal (B isoenzyme) and for the retaining alpha-glucosidase from rice: comparison with the appropriate monofluoride reveals a variable rate-retarding effect of the second fluorine atom on kcat./Km that correlates with other measures of oxocarbonium ion character in the transition state. 6. The difluoride is a substrate for the (retaining) alpha-glucosidase from yeast, but also gives an insidious mimicry of active-site-directed irreversible inhibition, which we tentatively attribute either to formation of the non-covalent complex or to the fluoroglucosyl-enzyme increasing the well-known tendency of this enzyme to come out of solution by adsorption on the walls of the vessel.