Department of General Chemistry, Belarusian State Medical University, Dzerzinskogo 83, Minsk, Belarus.
Biochemical Group of the Multidisciplinary Diagnostic Laboratory, Institute of Physiology of the National Academy of Sciences of Belarus, Minsk, Belarus.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Aug 5;257:119784. doi: 10.1016/j.saa.2021.119784. Epub 2021 Apr 8.
Fluorescence spectra of proteins and peptides are traditionally used to get an information on self-association of proteins and peptides, on their tertiary and quaternary structure. In this study it was shown that there are just three peaks of tryptophan fluorescence (at ∼308, at ∼330, and at ∼360 nm) in rough unsmoothed spectra of fluorescence of pure tryptophan in different solvents that change their heights depending on the polarity of a solvent. Two separate peaks at ∼330 nm and ∼360 nm are especially prominent in the spectrum of human epidermal growth factor. In contrast, in smoothed (either mathematically, or physically) spectra of Trp-containing proteins a single maximum of fluorescence varies between 330 and 360 nm. The theory of tryptophan fluorescence is discussed in light of three discrete peaks existence. A stabilizing hydrogen bond with aromatic system of benzene ring in the excited state is proposed as the cause of emission at ∼360 nm bringing Trp to the destabilized ground state. Emission from the destabilized excited state has a maximum at ∼330 nm if the ground state is destabilized, as well as if both states are stabilized. If the excited state is destabilized, while the ground state is stabilized by purely hydrophobic interactions, emitted light should have a maximum at ∼308 nm. The degree of hydrophilicity of tryptophan microenvironment is proposed to be measured as the ratio between the peak at 360 nm and the peak at 330 nm if the observed shifts are not "horizontal", but "vertical". The process of dissociation of hemagglutinin trimers from pandemic Influenza A(H1N1) virus is described as an example of the advantages of the proposed method.
蛋白质和肽的荧光光谱传统上用于获取有关蛋白质和肽自组装的信息，以及它们的三级和四级结构。在这项研究中表明，在不同溶剂中纯色氨酸荧光的原始未平滑光谱中只有三个色氨酸荧光峰（在∼308nm、∼330nm 和∼360nm 处），它们的高度取决于溶剂的极性。在人表皮生长因子的光谱中，∼330nm 和∼360nm 处的两个单独的峰特别突出。相比之下，在含有色氨酸的蛋白质的平滑（无论是数学上还是物理上）光谱中，荧光的单一最大值在 330nm 和 360nm 之间变化。根据存在三个离散峰的理论讨论了色氨酸荧光。在激发态下，与苯环芳香系统形成稳定氢键被提议为在∼360nm 处发射的原因，使色氨酸进入去稳定的基态。如果基态被去稳定，以及如果两个状态都被稳定，那么从去稳定的激发态发射的光在∼330nm 处具有最大值。如果激发态被去稳定，而基态被纯疏水性相互作用稳定，则发射光应在∼308nm 处具有最大值。提议将色氨酸微环境的亲水性程度测量为 360nm 峰与 330nm 峰的比值，如果观察到的位移不是“水平”，而是“垂直”。作为所提出方法的优点的示例，描述了血凝素三聚体从大流行性流感 A（H1N1）病毒中的解离过程。
