Farzami B, Mariam Y H, Jordan F
Biochemistry. 1977 Mar 22;16(6):1105-10. doi: 10.1021/bi00625a012.
The solvent polarity dependence of the interaction between thiamin and tryptophan was studied by spectrophotometric methods. The ultraviolet (UV) data clearly indicate that the interaction is weakened when the complex is transferred from water to aqueous ethanol or aqueous dioxane. The interaction of thiamin and tryptophan could also be detected by fluorescence-quenching studies (excitation of tryptophan at 287 nm, maximum emission at 348 nm). Appropriate treatment of the quenching data allowed dissection into static and dynamic contributions. A pyrimidine derivative related to thiamin, both in its neutral and protonated states, was shown to interact with tryptophan by fluorescence techniques, but not by UV. A thiazolium model was shown to interact with tryptophan by UV but was an inefficient quencher of the tryptophan fluorescence. Theoretical models are presented to explain the solvent dielectric constant dependence of the association constant between tryptophan and thiamin. Both electrostatic and dispersion forces are found to contribute to the stability of the complex.
采用分光光度法研究了硫胺素与色氨酸相互作用的溶剂极性依赖性。紫外（UV）数据清楚地表明，当配合物从水转移到乙醇水溶液或二氧六环水溶液时，相互作用减弱。硫胺素与色氨酸的相互作用也可以通过荧光猝灭研究来检测（色氨酸在287nm处激发，最大发射波长在348nm处）。对猝灭数据进行适当处理后，可以将其分解为静态和动态贡献。一种与硫胺素相关的嘧啶衍生物，无论是中性还是质子化状态，通过荧光技术显示与色氨酸相互作用，但通过紫外光则不然。噻唑鎓模型通过紫外光显示与色氨酸相互作用，但对色氨酸荧光的猝灭效率较低。提出了理论模型来解释色氨酸与硫胺素之间缔合常数对溶剂介电常数的依赖性。发现静电和色散力都对配合物的稳定性有贡献。
