Paselk R A, Levy D
Biochim Biophys Acta. 1976 Aug 9;439(2):479-91. doi: 10.1016/0005-2795(76)90085-4.
19F nuclear magnetic resonance spectroscopy has been used to study the effects of salts and denaturants on the structure and aggregation properties of several trifluoroacetyl derivatives of insulin. This technique has been shown to be a powerful tool in the study of specific sites on the protein molecule. Circular dichroic and sedimentation velocity studies were also carried out to aid in the interpretation of the magnetic resonance data. At pH 6.8 Zn2+ had no effect on the 19F magnetic resonance spectrum, however, citrate and acetate ions significantly sharpened the signal from the trifluoroacetyl probe at the N-terminal end (glycine A-1) of the insulin A chain. No alterations were observed in the S20,W value of circular dichroic spectra, suggesting that the probe had gained a considerable degree of motional freedom without changes in aggregation or conformational properties. In the absence of perturbants the trifluoroacetyl group on glycine A-1 showed considerably more motional freedom than on phenylalanine B-1. Guanidine hydrochloride and sodium dodecyl sulfate were used to study the unfolding of several trifluoroacetylinsulin derivatives. The results suggested differential alterations in the environments of the probes located at glycine A-1, phenylalanine B-1, and lysine B-29 in the insulin molecule as the concentration of perturbant was increased.
19F核磁共振光谱已被用于研究盐和变性剂对几种胰岛素三氟乙酰基衍生物的结构和聚集特性的影响。该技术已被证明是研究蛋白质分子上特定位点的有力工具。还进行了圆二色性和沉降速度研究，以辅助解释磁共振数据。在pH 6.8时，Zn2+对19F磁共振光谱没有影响，然而，柠檬酸根离子和醋酸根离子显著锐化了胰岛素A链N端（甘氨酸A-1）三氟乙酰基探针的信号。圆二色光谱的S20,W值没有观察到变化，这表明探针获得了相当程度的运动自由度，而聚集或构象特性没有改变。在没有干扰剂的情况下，甘氨酸A-1上的三氟乙酰基比苯丙氨酸B-1上的表现出更多的运动自由度。使用盐酸胍和十二烷基硫酸钠来研究几种三氟乙酰胰岛素衍生物的去折叠。结果表明，随着干扰剂浓度的增加，胰岛素分子中位于甘氨酸A-1、苯丙氨酸B-1和赖氨酸B-29处的探针环境发生了不同的变化。
