Lim A, Saderholm M J, Makhov A M, Kroll M, Yan Y, Perera L, Griffith J D, Erickson B W
Department of Chemistry, The University of North Carolina at Chapel Hill, 27599-3290, USA.
Protein Sci. 1998 Jul;7(7):1545-54. doi: 10.1002/pro.5560070708.
The betabellin target structure is a beta-sandwich protein consisting of two 32 residue beta-sheets packed against one another by interaction of their hydrophobic faces. The 32 residue chain of betabellin-15S (HSLTAKIpkLTFSIAphTYTCAV pkYTAKVSH, where p=DPro, k=DLys, and h=DHis) did not fold in water at pH 6.5. Air oxidation of betabellin-15S provided betabellin-15D, the 64 residue disulfide bridged two-chain molecule, which also remained unfolded in water at pH 6.5. By circular dichroic spectropolarimetry, the extent of beta structure observed for betabellin-15D increased with the pH and ionic strength of the solution and the betabellin-15D concentration. By electron microscopy, in 5.0 mM MOPS and 0.25 M NaCl at pH 6.9, betabellin-15D formed long narrow multimeric fibrils. A molecular model was constructed to show that the dimensions of these betabellin-15D fibrils are consistent with a single row of beta-sandwich molecules joined by multiple intersheet H-bonds.
β-珠蛋白的目标结构是一种β-折叠三明治蛋白,由两条含32个残基的β-折叠片层通过其疏水面的相互作用相互堆积而成。β-珠蛋白-15S(HSLTAKIpkLTFSIAphTYTCAV pkYTAKVSH,其中p = DPro,k = DLys,h = DHis)的32个残基链在pH 6.5的水中无法折叠。β-珠蛋白-15S的空气氧化产生了β-珠蛋白-15D,即一种含64个残基的通过二硫键桥接的双链分子,它在pH 6.5的水中也保持未折叠状态。通过圆二色光谱偏振法,观察到β-珠蛋白-15D的β结构程度随溶液的pH值、离子强度以及β-珠蛋白-15D浓度的增加而增加。通过电子显微镜观察,在pH 6.9的5.0 mM MOPS和0.25 M NaCl中,β-珠蛋白-15D形成了长而窄的多聚体纤维。构建了一个分子模型以表明这些β-珠蛋白-15D纤维的尺寸与由多个片层间氢键连接的单排β-折叠三明治分子一致。