Jordan J D, Dunbar R A, Bright F V
Department of Chemistry, Natural Sciences and Mathematics Complex, State University of New York at Buffalo 14260-3000, USA.
Anal Chem. 1995 Jul 15;67(14):2436-43. doi: 10.1021/ac00110a019.
We investigate acrylodan-labeled bovine and human serum albumin (BSA-Ac and HSA-Ac) entrapped within a tetramethylorthosilane-derived biogel composite. The effects of biogel aging and drying were studied by following the acrylodan steady-state and time-resolved emission, the decay of anisotropy, and the dipolar relaxation kinetics as a function of ambient storage time. The results indicate that there is a substantial amount of nanosecond and subnanosecond dipolar relaxation within the local environment surrounding cysteine-34 in both proteins, even when they are fully encapsulated in a dry biogel. Time-resolved anisotropy experiments show that the acrylodan residue and the protein are able to undergo nanosecond motion within the biogel. The semiangle through which the acrylodan can process is the same for a freshly formed biogel and the native protein in buffer. However, once the biogel begins to dry, the semiangle increases (approximately 20 degrees and 10 degrees for BSA-Ac and HSA-Ac, respectively). This suggests that the "pocket" hosting the acrylodan reporter group opens as the biogel dries.
我们研究了包裹于原硅酸四甲酯衍生的生物凝胶复合材料中的丙烯罗丹标记的牛血清白蛋白和人血清白蛋白（BSA-Ac和HSA-Ac）。通过追踪丙烯罗丹的稳态和时间分辨发射、各向异性衰减以及作为环境储存时间函数的偶极弛豫动力学，研究了生物凝胶老化和干燥的影响。结果表明，即使两种蛋白质完全包裹在干燥的生物凝胶中，其半胱氨酸-34周围局部环境内仍存在大量纳秒级和亚纳秒级的偶极弛豫。时间分辨各向异性实验表明，丙烯罗丹残基和蛋白质能够在生物凝胶内进行纳秒级运动。对于新形成的生物凝胶和缓冲液中的天然蛋白质，丙烯罗丹能够转动的半角是相同的。然而，一旦生物凝胶开始干燥，半角就会增大（BSA-Ac和HSA-Ac分别约为20度和10度）。这表明容纳丙烯罗丹报告基团的“口袋”会随着生物凝胶干燥而打开。
