Scientists of the Institute of Biophysics of ANAS have developed a method for characterizing proteins in solid form

The article of the young scientist of the Institute of Biophysics, Ph.D. Aytaj Mamedova and the director of the institute, corresponding member of ANAS Oktay Gasimov has been accepted for publication in the prestigious journal “Biochemistry and Biophysics Reports” published by “Elsevier”.

In the article entitled “ANS fluorescence: Potential to discriminate hydrophobic sites of proteins in solid states”, it is possible to characterize hydrophobic clusters of proteins in the solid form for the first time using the fluorescence properties of the ANS molecule (1-anilino-8-naphthalenesulfonate). Silk fibroin from Bombyx mori cocoons was used as a paradigm protein. ANS incorporated into the films of silk fibroin exhibits fluorescence with two-lifetime components that can be assigned to the patches and/or cavities with distinct hydrophobicities. Decay associated spectra (DAS) of ANS fluorescence from both sites could be fit to the single log-normal component indicating their homogeneity. ANS binding sites in the protein film are specific and could be saturated by ANS titration. ANS located in the binding site that exhibits the long-lifetime fluorescence is not accessible to the water molecules and its DAS stays homogeneously broadened upon hydration of the protein film. In contrast, ANS from the sites demonstrating the short-lifetime fluorescence is accessible to water molecules. In the hydrated films, solvent-induced fluctuations produce an ensemble of binding sites with similar characters. Therefore, upon hydration, the short-lifetime DAS becomes significantly red-shifted and inhomogeneously broadened. The similar spectral features have previously been observed for ANS complexed with globular proteins in solution. The data reveal the origin of the short-lifetime fluorescence component of ANS bound to the globular proteins in aqueous solution. Findings from this study indicate that ANS is applicable to characterize dehydrated as well as hydrated protein aggregates, amyloids relevant to amyloid diseases, such as Alzheimer’s, Parkinson, and prion diseases.

28 October 2020

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