We have carried out chemical shift perturbation titrations on three contrasting proteins. The resulting chemical shifts have been analysed to determine the best way to fit the data, and it is concluded that a simultaneous fitting of all raw shift data to a single dissociation constant is both the most accurate and the most precise method. It is shown that the optimal weighting of ¹⁵N chemical shifts to ¹H chemical shifts is protein dependent, but is around the consensus value of 0.14. We show that chemical shift changes of individual residues can be fit to give residue-specific affinities. Residues with affinities significantly stronger than average are found in close contact with the ligand and are suggested to form a rigid contact surface, but only when the binding involves little conformational change. This observation may be of value in analysing binding and conformational change.

我们对三种不同的蛋白质进行了化学位移扰动滴定。已分析产生的化学位移以确定拟合数据的最佳方法，并得出结论，将所有原始位移数据同时拟合到单个解离常数是最准确和最精确的方法。结果表明，¹⁵ N 化学位移的最佳权重变为¹H 化学位移取决于蛋白质，但在共识值 0.14 附近。我们表明，单个残基的化学位移变化可以适合给出残基特异性亲和力。发现与配体紧密接触的亲和力明显强于平均值的残基并建议形成刚性接触表面，但仅当结合涉及很少的构象变化时。这一观察结果可能对分析结合和构象变化有价值。