School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
J Inorg Biochem. 2010 Feb;104(2):211-3. doi: 10.1016/j.jinorgbio.2009.10.012. Epub 2009 Oct 23.
Glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a binuclear metallohydrolase that catalyzes the breakdown of a broad range of phosphate ester substrates, and it is of interest for its potential application in the destruction of organophosphate nerve agents and pesticides. The reaction mechanism of GpdQ has been proposed to involve a nucleophilic attack by a terminally bound hydroxide molecule. The hydroxide species bridging the two metal ions is suggested to activate the nucleophile, thus favoring a sequential rather than a processive mechanism of action. Here, the hydrolysis of the two ester bonds in the substrate bis(para-nitrophenyl) phosphate (bpNPP) is probed using (31)P NMR. The kinetic rates measured compare well with those determined spectrophotometrically. Furthermore, the data indicate that the diester bonds are cleaved in two separate (non-processive) reactions, indicating that only a single nucleophile (the terminal hydroxide molecule) is likely to be employed as a nucleophile for GpdQ.
来自产气肠杆菌的甘油磷酸二酯酶(GpdQ)是一种双核金属水解酶,能够催化广泛的磷酸酯底物的分解,因其在破坏有机磷神经毒剂和杀虫剂方面的潜在应用而受到关注。GpdQ 的反应机制已被提议涉及末端结合的氢氧根分子的亲核攻击。桥连两个金属离子的氢氧根物种被认为可以激活亲核试剂,从而有利于顺序而不是连续的作用机制。在这里,使用 (31)P NMR 探测了底物双(对硝基苯基)磷酸酯(bpNPP)中两个酯键的水解。测量的动力学速率与分光光度法测定的速率非常吻合。此外,数据表明,两个二酯键在两个单独的(非连续)反应中被切断,这表明 GpdQ 可能只使用单个亲核试剂(末端氢氧根分子)作为亲核试剂。