Fogolari F, Ragona L, Zetta L, Romagnoli S, De Kruif K G, Molinari H
Istituto Policattedra, Università degli Studi di Verona, Italy.
FEBS Lett. 1998 Oct 2;436(2):149-54. doi: 10.1016/s0014-5793(98)00936-3.
We have determined a crude structure of the apo form of bovine beta-lactoglobulin, a protein of 162 amino acid residues with a molecular mass of 18 kDa, at a low pH on the basis of data collected using only homonuclear 1H NMR spectroscopy. An ensemble of protein conformations was calculated with the distance-geometry algorithm for NMR applications (DYANA). The monomeric protein at low pH adopts a beta-barrel fold, well-superimposable on the structure determined by X-ray crystallography for the dimer at physiological pH. NMR evidence suggests the presence of disordered loop regions and terminal segments. Structural differences between the monomer at pH 2 and the dimer at pH 7, obtained by X-ray crystallography, are discussed, paying particular attention to surface electrostatic properties, in view of the high charge state of the protein at low pH.
我们基于仅使用同核1H NMR光谱收集的数据，在低pH条件下确定了牛β-乳球蛋白脱辅基形式的粗略结构，该蛋白由162个氨基酸残基组成，分子量为18 kDa。使用用于NMR应用的距离几何算法（DYANA）计算了蛋白质构象集合。低pH下的单体蛋白采用β-桶状折叠，与通过X射线晶体学确定的生理pH下二聚体的结构高度重叠。NMR证据表明存在无序的环区域和末端片段。鉴于蛋白质在低pH下的高电荷状态，讨论了通过X射线晶体学获得的pH 2下单体与pH 7下二聚体之间的结构差异，特别关注表面静电性质。
