通过傅里叶变换红外光谱法对钠钾ATP酶及其钠（E1）和钾（E2）复合物进行二级结构分析。

Secondary structural analysis of the Na(+),K(+)-ATPase and its Na(+) (E(1)) and K(+) (E(2)) complexes by FTIR spectroscopy.

作者信息

Neault J F, Malonga H, Diamantoglou S, Carpentier R, Stepp R L, Tajmir-Riahi H A

机构信息

Groupe de Recherche en Energie et Information Biomoléculaires, Université du Québec Trois-Rivières, Canada.

出版信息

J Biomol Struct Dyn. 2002 Oct;20(2):173-8. doi: 10.1080/07391102.2002.10506833.

DOI:10.1080/07391102.2002.10506833

PMID:12354069

Abstract

The Na(+),K(+)-ATPase is an integral membrane protein which transports sodium and potassium cations against an electrochemical gradient. The transport of Na(+) and K(+) ions is presumably connected to an oscillation of the enzyme between the two conformational states, the E(1) (Na(+)) and the E(2) (K(+)) conformations. The E(1) and E(2) states have different affinities for ligand interaction. However, the determination of the secondary structure of this enzyme in its sodium and potassium forms has been the subject of much controversy. This study was designed to provide a quantitative analysis of the secondary structure of the Na(+),K(+)-ATPase in its sodium (E(1)) and potassium (E(2)) states in both H(2)O and D(2)O solutions at physiological pH, using Fourier transform infrared (FTIR) with its self-deconvolution and second derivative resolution enhancement methods, as well as curve-fitting procedures. Spectroscopic analysis showed that the secondary structure of the sodium salt of the Na(+),K(+)-ATPase in H(2)O solution contains alpha-helix 19.8+/-1%, beta-sheet 25.6+/-1%, turn 9.1+/-1%, and beta-anti 7.5+/-1%, whereas in D(2)O solution, the enzyme shows alpha-helix 16.8+/-1%, beta-sheet 24.5+/-1.5%, turn 10.9+/-1%, beta-anti 9.8+/-1%, and random coil 38.0+/-2%. Similarly, the potassium salt in H(2)O solution contains alpha-helix 16.6+/-1%, beta-sheet 26.4+/-1.5%, turn 8.9+/-1%, and beta-anti 8.1+/-1%, while in D(2)O solution it shows alpha-helix 16.2+/-1%, beta-sheet 24.5+/-1.5%, turn 10.3+/-1%, beta-anti 9.0+/-1%, and random coil 40+/-2%. Thus the main differences for the sodium and potassium forms of the Na(+),K(+)-ATPase are alpha-helix 3.2% in H(2)O and 0.6% in D(2)O, beta-sheet (pleated and anti) 1.5% in H(2)O and random structure 2% (D(2)O), while for other minor components (turn structure), the differences are less than 1%.

摘要

钠钾ATP酶是一种整合膜蛋白，可逆电化学梯度转运钠和钾阳离子。钠和钾离子的转运可能与该酶在两种构象状态（E(1)（Na(+)）和E(2)（K(+)）构象）之间的振荡有关。E(1)和E(2)状态对配体相互作用具有不同的亲和力。然而，确定该酶钠型和钾型的二级结构一直是诸多争议的主题。本研究旨在使用傅里叶变换红外光谱（FTIR）及其自去卷积和二阶导数分辨率增强方法以及曲线拟合程序，对生理pH条件下H₂O和D₂O溶液中钠钾ATP酶的钠型（E(1)）和钾型（E(2)）状态的二级结构进行定量分析。光谱分析表明，H₂O溶液中钠钾ATP酶钠盐的二级结构包含α-螺旋19.8±1%、β-折叠25.6±1%、转角9.1±1%和β-反向平行7.5±1%，而在D₂O溶液中，该酶显示α-螺旋16.8±1%、β-折叠24.5±1.5%、转角10.9±1%、β-反向平行9.8±1%和无规卷曲38.0±2%。同样，H₂O溶液中的钾盐包含α-螺旋16.6±1%、β-折叠26.4±1.5%、转角8.9±1%和β-反向平行8.1±1%，而在D₂O溶液中它显示α-螺旋16.2±1%、β-折叠24.5±1.5%、转角10.3±1%、β-反向平行9.0±1%和无规卷曲40±2%。因此，钠钾ATP酶钠型和钾型的主要差异在于H₂O中α-螺旋为3.2%，D₂O中为0.6%；H₂O中β-折叠（褶皱和平行）为1.5%，D₂O中无规结构为2%；而对于其他次要成分（转角结构），差异小于1%。