Chen Lee, Shukla Nimesh, Cho Inha, Cohn Erin, Taylor Erika A, Othon Christina M
†Department of Physics, Wesleyan University, 265 Church Street, Middletown, Connecticut 06459, United States.
‡Department of Chemistry, Wesleyan University, 52 Lawn Avenue, Middletown, Connecticut 06459, United States.
J Phys Chem Lett. 2015 Apr 16;6(8):1441-6. doi: 10.1021/acs.jpclett.5b00442. Epub 2015 Apr 2.
Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence anisotropy. Tryptophan exhibits rotational diffusion proportional to the measured bulk viscosity for sucrose solutions over a wide range of concentrations, consistent with a Stokes-Einstein model. For sucralose solutions, however, the diffusion is dependent on the concentration, strongly diverging from the viscosity predictions, and results in heterogeneous rotational diffusion.
三氯蔗糖是一种常用的人工甜味剂，在与生物分子相互作用方面，其行为与天然二糖对应物蔗糖有很大不同。研究发现，溶液中三氯蔗糖的存在会破坏两种模型蛋白质系统的天然结构：球状蛋白牛血清白蛋白和酶葡萄球菌核酸酶。这些蛋白质的解链温度随三氯蔗糖浓度呈线性下降。我们将这种去稳定作用与分子极性的增加联系起来。这种强极性性质表现为利用时间分辨荧光各向异性对色氨酸激发态旋转扩散施加的大介电摩擦。在很宽的浓度范围内，色氨酸的旋转扩散与蔗糖溶液的测量体粘度成正比，这与斯托克斯 - 爱因斯坦模型一致。然而，对于三氯蔗糖溶液，扩散取决于浓度，与粘度预测有很大偏差，并导致非均匀旋转扩散。
