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28 February 2011 Photoinduced unfolding of tubulin dimers bound to meso-tetrakis (sulfonatophenyl) porphyrin
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The function of a protein is correlated to its structure. Thus, the ability to control the structure by unfolding the protein becomes of considerable interest. One novel method of unfolding a protein involves using a light activated ligand bound to the protein which then triggers a photochemical reaction. Many porphyrins are natural products and are cell-friendly within certain limits of concentration. Many of them have been used for Photodynamic Therapy (PDT) of cancer. The specific porphyrin used in this study is meso-tetrakis (sulfonatophenyl) porphyrin (TSPP). In this study we investigated the binding of TSPP to Tubulin and the effects of irradiating the porphyrin/protein complex in an attempt to induce unfolding of Tubulin. Tubulin is an important protein which forms microtubules and has been the target of many anticancer therapies. A combination of various spectroscopic methods can be used to gain insight into the structural changes induced by the photosensitizer on the protein and provide a blueprint of the molecular interactions. Absorption and fluorescence spectroscopy yields information on how the electronic transition energy levels may be changing. Resonance Raman spectroscopy (RRS) provides structural information based on the changes of the vibrational modes of the ligand and circular dichroism (CD) probes the secondary structure of the protein. Thus by taking spectroscopic measurements of the protein/porphyrin complex before and after irradiation we can obtain structural information of the effects induced by light absorption. The results indicate that there is indeed significant unfolding of Tubulin as a result of irradiating the bound Porphyrin.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brady McMicken and Lorenzo Brancaleon "Photoinduced unfolding of tubulin dimers bound to meso-tetrakis (sulfonatophenyl) porphyrin", Proc. SPIE 7897, Optical Interactions with Tissue and Cells XXII, 78971Y (28 February 2011);

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