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首页> 外文期刊>International Journal of Biological Macromolecules: Structure, Function and Interactions >Effects of pH and salt environment on the association of beta-lactoglobulin revealed by intrinsic fluorescence studies
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Effects of pH and salt environment on the association of beta-lactoglobulin revealed by intrinsic fluorescence studies

机译：pH和盐环境对固有荧光研究揭示的β-乳球蛋白缔合的影响

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摘要

The effects of pH, ionic strength and heat on the structure of beta-lactoglobulin (beta-lg) have been investigated by studying the intrinsic tryptophan fluorescence of the protein. Between pH 2 and 9, for sodium chloride concentrations varying from 0.0 to 0.2 M, the position of the fluorescence emission maximum at 20 degrees C remained constant at 328 nm, suggesting that the hydrophobic environment of the fluorophores remained unchanged. The fluorescence intensity increased significantly at pH 2, 7 and 9 on reducing the NaCl concentration of the solutions. The most likely explanation for this, supported by recent light scattering data, is that the presence of NaCl is necessary for beta-lg to dimerize. At the higher NaCl concentrations it was found that dimerization accompanied a reduction in fluorescence intensity. Thus, dissociation appears to reduce the self-quenching of tryptophan residues that occurs within the dimer. The fluorescence of solutions heated below the denaturation temperature reflected the state of association of the protein molecules. Above the denaturation temperature and associated with protein aggregation, an irreversible increase in intrinsic tryptophan fluorescence was observed. We also report what we believe to be the first front-face fluorescence measurements on globular protein gels, showing effects of pH and NaCl concentration. (C) 1998 Elsevier Science B.V. [References: 46]
机译：通过研究蛋白质的固有色氨酸荧光，研究了pH，离子强度和热量对β-乳球蛋白（β-lg）结构的影响。在pH值2和9之间，对于氯化钠浓度从0.0到0.2 M的变化，最大荧光发射位置在20摄氏度时保持在328 nm不变，这表明荧光团的疏水环境保持不变。在降低溶液的NaCl浓度时，在pH 2、7和9时，荧光强度显着增加。最新的光散射数据支持的对此最可能的解释是，NaCl的存在对于β-Ig的二聚化是必需的。发现在较高的NaCl浓度下，二聚化伴随荧光强度的降低。因此，解离似乎减少了二聚体中发生的色氨酸残基的自猝灭。加热至低于变性温度的溶液的荧光反映了蛋白质分子的缔合状态。高于变性温度并与蛋白质聚集有关，观察到固有色氨酸荧光不可逆地增加。我们还报告了我们认为是球形蛋白质凝胶的第一个正面荧光测量结果，显示了pH和NaCl浓度的影响。 （C）1998 Elsevier Science B.V. [参考：46]

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