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首页> 外文期刊>Journal of Molecular Biology >Sequence and crystal structure determination of a basic phospholipase A2from common krait (Bungarus caeruleus) at 2.4 angstrom resolution:Identification and characterization of its pharmacological sites
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Sequence and crystal structure determination of a basic phospholipase A2from common krait (Bungarus caeruleus) at 2.4 angstrom resolution:Identification and characterization of its pharmacological sites

机译：普通（Bungarus caeruleus）中碱性磷脂酶A2的序列和晶体结构测定，分辨率为2.4埃：其药理位点的鉴定和表征

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摘要

This is the first phospholipase A2 (PLA2) structure from the family of kraits. The protein was isolated from Bungarus caeruleus (common krait) and the primary sequence was determined using cDNA approach. Three-dimensional structure of this presynaptic neurotoxic PLA2 from group I has been determined by molecular replacement method using the model of PLA2 component of beta2-bungarotoxin (Bungarus multicinctus) and refined using CNS package to a final R-factor of 20.1% for all the data in resolution range 20.0-2.4 Angstrom. The final refined model comprises 897 protein atoms and 77 water molecules. The overall framework of krait phospholipase A2 with three long helices and two short antiparallel beta -strands is extremely similar to those observed for other group PLA2s. However, the critical parts of PLA2 folding are concerned with its various functional loops. The conformations of these loops determine the efficiency of enzyme action and presence/absence of various pharmacological functions. In the present structure calcium-binding loop is occupied by a sodium ion with a 7-fold co-ordination. The conformation of loop 55-75 in krait PLA2 corresponds to a very high activity of the enzyme. A comparison of its sequence with multimeric PLA2s clearly shows the absence of critical residues such as Tyr3, Trp61 and Phe64, which are involved in the multimerization of PLA2 molecules. The protein shows anticoagulant and neurotoxic activities.
机译：这是来自Kraits家族的第一个磷脂酶A2（PLA2）结构。该蛋白是从Bergarus caeruleus（常见的krait）中分离得到的，并且使用cDNA方法确定了一级序列。已经通过分子置换方法使用β2-邦加罗毒素（Bungarus multicinctus）的PLA2组分模型确定了第一组突触前神经毒性PLA2的三维结构，并使用CNS包装对其进行了精制，最终所有化合物的R因子均为20.1％分辨率范围为20.0-2.4埃的数据。最终的精炼模型包含897个蛋白质原子和77个水分子。具有三个长螺旋和两个短反平行β链的Krait磷脂酶A2的总体框架与其他PLA2s观察到的极其相似。但是，PLA2折叠的关键部分涉及其各种功能循环。这些环的构象决定了酶作用的效率以及各种药理功能的存在与否。在本结构中，钙结合环被具有7倍配位的钠离子占据。 krait PLA2中55-75环的构象对应于该酶的极高活性。其序列与多聚PLA2的序列比较清楚地表明，不存在关键残基，例如Tyr3，Trp61和Phe64，它们与PLA2分子的多聚化有关。该蛋白质显示抗凝和神经毒性活性。

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