Measurement of SDS micelle-peptide association using 1H NMR chemical shift analysis and pulsed field gradient NMR spectroscopy
Measurement of SDS micelle-peptide association using 1H NMR chemical shift analysis and pulsed field gradient NMR spectroscopy
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DOI：
10.1021/ac971011m
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发表时间：
1998-04-01
影响因子：
7.4
通讯作者：
Larive, CK
中科院分区：
文献类型：
--
作者：
Orfi, L;Lin, MF;Larive, CK
用H-1核磁共振化学位移分析法研究了甘氨酰组氨酸甘氨酸(GHG)和苯丙氨酰组氨酸苯丙氨酸(FHF)这两种简单三肽与十二烷基硫酸钠(SDS)胶束的结合作用，并用脉冲场梯度谱测定了它们的自扩散系数。几个GHG共振峰的化学位移随浓度的变化而变化，表明多肽与胶束之间存在相互作用，此外，观察到的GHG扩散系数随浓度的下降表明多肽与十二烷基硫酸钠胶束的结合。在H-1化学位移和扩散时间尺度上，自由GHG和胶束结合的GHG都是快速交换的，通过分析组氨酸C2和C4共振的浓度依赖关系，确定了GHG与SDS胶束结合的平衡常数分别为17+/-5和24+/-6M-1，通过分析化学位移数据得到的平衡常数的精度受到观察到的微小化学位移变化的限制。对扩散系数的浓度依赖性进行分析，得出平衡常数为17+/-1M-1。疏水性越强的肽，FHF与SDS胶束的结合越强，因为在这些溶液中游离FHF的比例很小，所以不可能通过分析H-1化学位移或扩散系数数据来确定FHF与SDS胶束相互作用的形成常数。通过分析在没有肽的情况下SDS在0.10M Na2C2O4缓冲液中的扩散系数，确定了SDS的CMC为5.4+/-0.1 mm。也可以从测量的作为SDS浓度的函数的GHG和FHF扩散系数中提取SDCMC，根据GHG扩散数据确定CMC，5.7+/-0.2 mm，与SDS扩散系数在5.0 mM GHG溶液中的扩散系数(5.2+/-0.1 mm)符合得很好，由FHF扩散数据测得的较小的CMC为4.1+/-0.1 mm，可能反映了在主体溶液中胶束形成之前，十二烷基硫酸钠与多肽的某种结合。
The binding of two simple tripeptides, glycyl-histidyl-glycine (GHG) and phenylalanyl-histidyl-phenylalanine (FHF) with SDS micelles was examined using H-1 NMR chemical shift analysis and self-diffusion coefficients measured with pulsed-field gradient NMR spectroscopy, The presence of GHG or FHF did not appear to significantly affect the critical micelle concentration (cmc) or the average size of the SDS micelles formed. The chemical shifts of several of the GHG resonances change as a function of SDS concentration, indicating an interaction between the peptide and the micelles, In addition, the concentration-dependent decrease observed for the GHG diffusion coefficients suggests association of the peptide with SDS micelles. The free and micelle-associated GHG are in fast exchange on both the H-1 chemical shift and diffusion time scales, The equilibrium constant for the binding of GHG to SDS micelles was determined from the analysis of the concentration dependence of the histidine C2 and C4 resonances to be 17 +/- 5 and 24 +/- 6 M-1, respectively, The precision of the equilibrium constants obtained by analysis of the chemical shift data is limited by the small chemical shift changes observed. Analysis of the concentration dependence of the diffusion coefficients produced an equilibrium constant of 17 +/- 1 M-1. The more hydrophobic peptide, FHF is strongly associated with the SDS micelles, Because the fraction of free FHF is small in these solutions, it was not possible to determine a formation constant for the interaction of FHF with the SDS micelles by analysis of either the H-1 chemical shift or diffusion coefficient data, The cmc of SDS in 0.10 M Na2C2O4 buffer was determined to be 5.4 +/- 0.1 mM by analysis of the SDS diffusion coefficients in the absence of the peptides, The SDS cmc could also be extracted from the GHG and FHF diffusion coefficients measured as a function of the SDS concentration, The cmc determined from the GHG diffusion data, 5.7 +/- 0.2 mM, is in good agreement with the value determined from analysis of the SDS diffusion coefficients in the 5.0 mM GHG solution, 5.2 +/- 0.1 mM, The smaller cmc determined from the FHF diffusion data, 4.1 +/- 0.1 mM, may reflect some association of the SDS with the peptide prior to micelle formation in bulk solution.