Hancock W S, Knighton D R, Napier J R, Harding D R, Venable R
J Chromatogr. 1986 Sep 26;367(1):1-8. doi: 10.1016/s0021-9673(00)94811-8.
The effect of temperature was investigated on the reversed-phase chromatography of a synthetic lipid associating peptide (LAP), with the following sequence (LESFLKSWLSALEQALKA) and on insulin. The LAP was chromatographed on a muBondapak-alkylphenyl column with 1% aq. triethylammonium phosphate, pH 3.2-2-propanol (80:20) as the isocratic mobile phase. The insulin was separated on a Resolve-C18 column with a mobile phase that contained 0.1 M sodium phosphate, pH 2.0-acetonitrile (71.5:28.5). With the LAP the Van't Hoff plot (In k' vs. 1000/T) was linear and the value of enthalpy for association of the peptide with the reversed-phase column was large and negative. The phase ratio was estimated for the column used in the separation and then derivation of the corresponding entropic term demonstrated that the association was enthalpy and not entropy drive. By contrast the corresponding Van't Hoff plot derived or the insulin study was non-linear and with a positive slope. Further study indicated that the formation of the insulin-reversed phase complex could be attributed to a favorable entropy change. It is probable that the non-classical thermodynamics observed during the insulin chromatography could be related to conformational changes in the insulin structure during the chromatographic process.
研究了温度对一种合成脂质缔合肽（LAP）（序列为LESFLKSWLSALEQALKA）和胰岛素反相色谱的影响。LAP在μBondapak - 烷基苯基柱上进行色谱分析，以1%的磷酸三乙铵水溶液（pH 3.2） - 2 - 丙醇（80:20）作为等度流动相。胰岛素在Resolve - C18柱上分离，流动相为含0.1 M磷酸钠（pH 2.0） - 乙腈（71.5:28.5）。对于LAP，范特霍夫图（ln k'对1000/T）呈线性，肽与反相柱缔合的焓值大且为负。估算了分离所用柱的相比，然后推导相应的熵项表明缔合是由焓驱动而非熵驱动。相比之下，胰岛素研究得到的相应范特霍夫图是非线性的且斜率为正。进一步研究表明胰岛素 - 反相复合物的形成可归因于有利的熵变。胰岛素色谱过程中观察到的非经典热力学很可能与色谱过程中胰岛素结构的构象变化有关。
