Abrecht H, Goormaghtigh E, Ruysschaert J M, Homble F
Laboratoire de Physiologie Végétale, CP 206/2, Faculté des Sciences, Université Libre de Bruxelles, Bld du Triomphe, B-1050 Brussels, Belgium.
J Biol Chem. 2000 Dec 29;275(52):40992-9. doi: 10.1074/jbc.M006437200.
Two VDAC (voltage-dependent anion-selective channel) isoforms were purified from seed cotyledons of Phaseolus vulgaris by chromatofocusing chromatography. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy was used to study the structural properties of the two isoforms reconstituted in a mixture of asolectin and 5% stigmasterol. The IR spectra of the two VDAC isoforms were highly similar indicating 50 to 53% anti-parallel beta-sheet. The orientation of the beta-strands relative to the barrel axis was calculated from the experimentally obtained dichroic ratios of the amide I beta-sheet component and the amide II band. Comparing the IR spectra of the reconstituted VDAC isoforms with the IR spectra of the bacterial porin OmpF, for which a high resolution structure is available, provided evidence for a general structural organization of the VDAC isoforms similar to that of bacterial porins. Hydrogen-deuterium exchange measurements indicated that the exchange of the amide protons occurs to a higher extent in the two VDAC isoforms than in the OmpF porin.
通过色谱聚焦色谱法从菜豆种子子叶中纯化出两种电压依赖性阴离子选择性通道（VDAC）亚型。采用衰减全反射傅里叶变换红外（ATR-FTIR）光谱法研究了在大豆卵磷脂和5%豆甾醇混合物中重构的这两种亚型的结构特性。两种VDAC亚型的红外光谱高度相似，表明含有50%至53%的反平行β-折叠。根据实验获得的酰胺Iβ-折叠成分和酰胺II带的二向色比，计算了β-链相对于桶状轴的方向。将重构的VDAC亚型的红外光谱与具有高分辨率结构的细菌孔蛋白OmpF的红外光谱进行比较，为VDAC亚型与细菌孔蛋白相似的一般结构组织提供了证据。氢-氘交换测量表明，两种VDAC亚型中酰胺质子的交换程度高于OmpF孔蛋白。
