海南捕鸟蛛毒素-I(HNTX-I)的~1H-NMR信号归属和二级结构分析(英文)

SEQUENCE-SPECIFIC ASSIGNMENT OF 1H-NMR RESONANCE AND DETERMINATION OF THE SECONDARY STRUCTURE OF HAINANTOXIN-I

海南捕鸟蛛毒素-I(HNTX-I)是从海南捕鸟蛛(Ornithoctonus hainana)的粗毒中纯化的一种新型神经毒素。应用二维1H-NMR.技术研究HNTX-I的溶液结构特点,通过分析水和重水中的DOF-COSY、TOCSY和NOESY谱,识别出HNTX-I全部33个氨基酸残基自旋体系;通过NOESY谱中的dαN、dβN、dNN和Dαδ联系完成了序列专一的谱峰归属,从而确认了HNTX-I所有的主链质子和大于96％的侧链质子的化学位移。并通过分析3JNH-CaH耦合常数、序列间的NOE联系以及慢氢交换质子等,确定HNTX-I的二级结构主要是由三股反平行的β-折迭组成(Lys7-Cys9,Tyr20-Asn23和Trp28-Val31),这些结构特点与已经探明结构的其它蜘蛛毒素的基本相同。这些结果为完全解析HNTX-I的溶液三维结构奠定了基础。

Hainantoxin-I (HNTX-I ) is an insect blocker of voltage-gated sodium channel isolated from the venom of the Chinese bird spider Ornithoctonus hainana (early named Selenocosmia hainana). The three-dimensional conformation of HNTX-I in aqueous solution was determined using two-dimensional 'H NMR techniques. The complete sequence-specific assignments of proton resonance in the 'H-NMR spectra of HNTX-1 were obtained by analyzing a series of 2D spectra, including double-quantum-filtered correlation spectroscopy (DQF-COSY), total correlated spectroscopy (TOCSY) and nuclear overhauser effect spectroscopy (NOESY) in H2O and D2O. All the backbone protons and more than 96% of the side-chain protons were identified by daN,, dN, dnn and da connectivities in NOESY spectrum. Furthermore, it was found that the main element of the secondary structure of HNTX-1 is a short triple-stranded antiparallel [3-sheet with Lys7-Cys9, Tyr20-Asn23 and Trp28-Val31, based on 3JNH-CaH coupling constants, sequential NOE connectivities and slowly exchanging amide protons. These characters of the secondary structure of HNTX-1 are similar to those of HWTX-I, SHL-I and HWTX-IV, which have known solution structures. These results provide a basis for the further determination of the solution conformation of HNTX-1 .