阴离子与泛素分子的结合。
Anion binding to the ubiquitin molecule.
作者信息
Makhatadze G I, Lopez M M, Richardson J M, Thomas S T
机构信息
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409-1061, USA.
出版信息
Protein Sci. 1998 Mar;7(3):689-97. doi: 10.1002/pro.5560070318.
Effects of different salts (NaCl, MgCl2, CaCl2, GdmCl, NaBr, NaClO4, NaH2PO4, Na2SO4) on the stability of the ubiquitin molecule at pH 2.0 have been studied by differential scanning calorimetry, circular dichroism, and Tyr fluorescence spectroscopies. It is shown that all of the salts studied significantly increase the thermostability of the ubiquitin molecule, and that this stabilization can be interpreted in terms of anion binding. Estimated thermodynamic parameters of binding for Cl- show that this binding is relatively weak (Kd = 0.15 M) and is characterized by a negative enthalpy of -15 kJ/mol per site. Particularly surprising was the observed stabilizing effect of GdmCl through the entire concentration range studied (0.01-2 M), however, to a lesser extent than stabilization by NaCl. This stabilizing effect of GdmCl appears to arise from the binding of Cl- ions. Analysis of the observed changes in the stability of the ubiquitin molecule in the presence of GdmCl can be adequately described by combining the thermodynamic model of denaturant binding with Cl- binding effects.
通过差示扫描量热法、圆二色性和酪氨酸荧光光谱法研究了不同盐（氯化钠、氯化镁、氯化钙、盐酸胍、溴化钠、高氯酸钠、磷酸二氢钠、硫酸钠）对泛素分子在pH 2.0时稳定性的影响。结果表明，所有研究的盐都显著提高了泛素分子的热稳定性，并且这种稳定性可以通过阴离子结合来解释。氯离子结合的估计热力学参数表明，这种结合相对较弱（解离常数Kd = 0.15 M），每个位点的结合焓为 -15 kJ/mol。特别令人惊讶的是，在所研究的整个浓度范围（0.01 - 2 M）内，盐酸胍都表现出稳定作用，不过其程度低于氯化钠的稳定作用。盐酸胍的这种稳定作用似乎源于氯离子的结合。结合变性剂结合的热力学模型和氯离子结合效应，可以充分描述在盐酸胍存在下观察到的泛素分子稳定性变化。
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