Deshpande S S, Damodaran S
Department of Food Science, University of Wisconsin, Madison 53706.
J Protein Chem. 1991 Feb;10(1):103-15. doi: 10.1007/BF01024660.
The denaturation behavior of phaseolin in urea, guanidine hydrochloride, and sodium dodecyl sulfate solutions was examined by monitoring changes in the intrinsic fluorescence of tryptophan and tyrosyl residues. Changes in various fluorescence parameters, such as quantum yield, emission maximum, spectral half-width, fluorescence depolarization, and fluorescence quenching by acrylamide, have indicated that while phaseolin is relatively stable up to 8 M urea, it is completely destabilized in 6 M guanidine hydrochloride and 6 mM sodium dodecyl sulfate. Furthermore, while the denaturation of phaseolin in urea solutions followed a two-step process, that in guanidine hydrochloride and sodium dodecyl sulfate followed a single-step process. While the accessibility of tryptophan residues to the nonionic acrylamide quencher is almost 100% in 6 M guanidine hydrochloride and 6 mM sodium dodecyl sulfate, only about 72% was accessible in 8 M urea compared to 52% in native phaseolin. The results presented here suggest that the protomeric structure of phaseolin is quite stable to changes in the environment. This structural stability may be partly responsible for its resistance to proteolysis by various proteinases.
通过监测色氨酸和酪氨酸残基的固有荧光变化，研究了菜豆蛋白在尿素、盐酸胍和十二烷基硫酸钠溶液中的变性行为。各种荧光参数的变化，如量子产率、发射最大值、光谱半高宽、荧光去极化以及丙烯酰胺引起的荧光猝灭，表明虽然菜豆蛋白在高达8M尿素中相对稳定，但在6M盐酸胍和6mM十二烷基硫酸钠中会完全失稳。此外，菜豆蛋白在尿素溶液中的变性遵循两步过程，而在盐酸胍和十二烷基硫酸钠中则遵循一步过程。在6M盐酸胍和6mM十二烷基硫酸钠中，色氨酸残基对非离子丙烯酰胺猝灭剂的可及性几乎为100%，而在8M尿素中只有约72%可及，天然菜豆蛋白中为52%。此处给出的结果表明，菜豆蛋白的原体结构对环境变化相当稳定。这种结构稳定性可能部分解释了其对各种蛋白酶水解的抗性。
