Structure of HI-6*sarin-acetylcholinesterase determined by X-ray crystallography and molecular dynamics simulation: reactivator mechanism and design.
Structure of HI-6*sarin-acetylcholinesterase determined by X-ray crystallography and molecular dynamics simulation: reactivator mechanism and design.
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DOI：
10.1371/journal.pone.0005957
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发表时间：
2009-06-18
期刊：
影响因子：
3.7
通讯作者：
Pang YP
中科院分区：
文献类型：
--
作者：
Ekström F;Hörnberg A;Artursson E;Hammarström LG;Schneider G;Pang YP
有机膦酸盐如甲基氟化膦异丙酯（沙林）是剧毒的，因为它们使乙酰胆碱酯酶（AChE）的催化丝氨酸残基膦化，而乙酰胆碱酯酶是人类和其他物种所必需的酶。设计有效的乙酰胆碱酯再活化剂作为各种有机膦酸盐的解毒剂，需要了解再活化剂如何与磷酸化的乙酰胆碱酯相互作用。但是，由于三个主要挑战，迄今为止还没有这种资料。首先，再激活剂通常是灵活的，以便从基态变为过渡态以再激活；这种灵活性阻碍了与本质上无序的有效再活化剂复合物中乙酰胆碱酯酶晶体结构的测定。其次，再激活发生在再激活剂与磷酸化的乙酰胆碱酯酶结合的时候。第三，磷偶联物可以产生再活化抗性。我们已经确定了晶体学条件，从而确定了沙林老化共轭小鼠AChE与[(E)-[1-[（4-氨基酰基吡啶-1- 1-酰基）甲氧基甲基]吡啶-2-酰基]甲基]二氯化氧氮（HI-6）配合物的晶体结构，分辨率为2.2 Å。在该结构中，HI-6的羧基氨基吡啶环被Tyr124和Trp286夹在中间，但肟吡啶环是无序的。通过晶体学和微秒分子动力学模拟相结合，我们确定了HI-6的肟-吡啶环结构，结果表明HI-6的肟基可以与沙林异丙醚氧形成氢键网络，水分子可以与催化组氨酸残基形成氢键，随后将肟脱质子进行再活化。这些结果为HI-6的再活化机理和更好的再活化剂的设计提供了新的思路。
Organophosphonates such as isopropyl metylphosphonofluoridate (sarin) are extremely toxic as they phosphonylate the catalytic serine residue of acetylcholinesterase (AChE), an enzyme essential to humans and other species. Design of effective AChE reactivators as antidotes to various organophosphonates requires information on how the reactivators interact with the phosphonylated AChEs. However, such information has not been available hitherto because of three main challenges. First, reactivators are generally flexible in order to change from the ground state to the transition state for reactivation; this flexibility discourages determination of crystal structures of AChE in complex with effective reactivators that are intrinsically disordered. Second, reactivation occurs upon binding of a reactivator to the phosphonylated AChE. Third, the phosphorous conjugate can develop resistance to reactivation. We have identified crystallographic conditions that led to the determination of a crystal structure of the sarinnonaged-conjugated mouse AChE in complex with [(E)-[1-[(4-carbamoylpyridin-1-ium-1-yl)methoxymethyl]pyridin-2-ylidene]methyl]-oxoazanium dichloride (HI-6) at a resolution of 2.2 Å. In this structure, the carboxyamino-pyridinium ring of HI-6 is sandwiched by Tyr124 and Trp286, however, the oxime-pyridinium ring is disordered. By combining crystallography with microsecond molecular dynamics simulation, we determined the oxime-pyridinium ring structure, which shows that the oxime group of HI-6 can form a hydrogen-bond network to the sarin isopropyl ether oxygen, and a water molecule is able to form a hydrogen bond to the catalytic histidine residue and subsequently deprotonates the oxime for reactivation. These results offer insights into the reactivation mechanism of HI-6 and design of better reactivators.
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影响因子：
5.8
作者：
ELLMAN, GL;COURTNEY, KD;FEATHERSTONE, RM
通讯作者：
FEATHERSTONE, RM
影响因子：
5.8
作者：
Ekstrom, Fredrik;Pang, Yuan-Ping;Borjegren, Susanne
通讯作者：
Borjegren, Susanne
影响因子：
5.6
作者：
Eyal, E;Gerzon, S;Sobolev, V
通讯作者：
Sobolev, V
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
56.9
作者：
GILSON, MK;STRAATSMA, TP;SUSSMAN, JL
通讯作者：
SUSSMAN, JL