Knubovets T, Osterhout J J, Klibanov A M
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Biotechnol Bioeng. 1999 Apr 20;63(2):242-8.
The structure of the model protein hen egg-white lysozyme dissolved in water and in five neat organic solvents (ethylene glycol, methanol, dimethylsulfoxide (DMSO), formamide, and dimethylformamide (DMF)) has been examined by means of 1H NMR and circular dichroism (CD) spectroscopies. The NMR spectra of lysozyme reveal the lack of a defined tertiary structure in all five organic solvents, although the examination of line widths suggests the possibility of some ordered structure in ethylene glycol and in methanol. The near-UV CD spectra of the protein suggest no tertiary structure in lysozyme dissolved in DMSO, formamide, and DMF, while a distinctive (albeit less pronounced than in water) tertiary structure is seen in ethylene glycol and a drastically changed one in methanol. A highly developed secondary structure was observed by far-UV CD in ethylene glycol and methanol; interestingly, the alpha-helix content of the protein in both was greater than in water, while the beta-structure content was lower. (Solvent absorbance in the far-UV region prevents conclusions about the secondary structure in DMSO, formamide and DMF.)
利用核磁共振氢谱（1H NMR）和圆二色光谱（CD），研究了溶解于水以及五种纯有机溶剂（乙二醇、甲醇、二甲基亚砜（DMSO）、甲酰胺和二甲基甲酰胺（DMF））中的模型蛋白鸡蛋清溶菌酶的结构。溶菌酶的核磁共振谱表明，在所有五种有机溶剂中均不存在明确的三级结构，不过对线宽的检测表明，在乙二醇和甲醇中可能存在一些有序结构。蛋白质的近紫外CD光谱表明，溶解于DMSO、甲酰胺和DMF中的溶菌酶不存在三级结构，而在乙二醇中可观察到独特的（尽管不如在水中明显）三级结构，在甲醇中则观察到显著变化的三级结构。通过远紫外CD在乙二醇和甲醇中观察到高度发达的二级结构；有趣的是，两者中蛋白质的α-螺旋含量均高于在水中的含量，而β-结构含量则较低。（远紫外区域的溶剂吸收妨碍了对DMSO、甲酰胺和DMF中二级结构的推断。）
