中等规模多肽分子的2DNOESY实验问题

2D NOESY EXPERIMENTAL PROBLEMS OF MEDIUM-SIZED PEPTIDES

由于中等规模多肽在水溶液中运动的特殊性（ω＿０τ＿ｃ≈１），２ＤＮＯＥＳＹ谱上往往得不到相关讯息（采用合理的混合时间），而降低温度的余地也很小·本工作将少量氘代甲醇加到水溶液中，并将实验温度降到零下，实验取得成功。例如从一个九肽和一个十一肽的ＮＯＥＳＹ实验得到了很多残基内和残基间的ＮＯＥＳＹ相关讯息，足以作出归属并进一步计算质子间距离．

The main difficulty in 2D NOESY of mcdium-sized peptdes is lacking of cross-peaks， espccially in the region related with NH， For solving this problem， theseauthors use a mixed solvent，CD_3OD／H_2O， to dissolve peptides，which allows NMRmeasurements at low temperature.The increased viscosity of solution and the correlationtimes by low-temperature measurements made a lot of intra-and inter-residueNOES observable， which helped us unambiguously complete the assigmnents of anonapeptide and an undccapcptide， and further in calculation of H-Hdistances.