Photosensitized Effects of Rose Bengal on Structure and Function of Lens Protein "Alpha-Crystallin" |
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Authors: | Tareq Youssef Mohamed Kassem Tarek Abdella Mohamed A Harith Francesco Lenci |
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Institution: | National Institute of Laser Enhanced Sciences (NILES), Cairo University, Giza, Egypt; CNR Istituto BioFisica, Via G. Moruzzi 1, Pisa, Italy |
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Abstract: | The conformational changes of the bovine lens protein "α-crystallin" have been investigated in the presence of the photosensitizer Rose Bengal (RB), in the dark as well as after visible light irradiation. Absorption and fluorescence emission spectra of RB 5 × 10−6 m ] and Fourier transform-IR spectra of α-crystallin 5 mg mL−1] were significantly altered upon RB α-crystallin complex formation. RB was found to bind to α-crystallin in a molecular pocket characterized by a low polarity, with Trp most likely involved in this interaction. The binding constant ( K b) has been estimated to be of the order of 2.5 (mg/mL)−1. The intrinsic fluorescence of α-crystallin was quenched through both dynamic and static mechanisms. Light-induced photosensitized effects showed structural modifications in α-crystallin, including tertiary and secondary structure (an increase in unordered structure) alterations. Notwithstanding those photoinduced structural variations detected in α-crystallin when complexed with RB, the protein still retains its ability to play the role of chaperone for β-crystallin. |
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