Premium
Photoinduced partial unfolding of tubulin bound to meso‐tetrakis(sulfonatophenyl) porphyrin leads to inhibition of microtubule formation in vitro
Author(s) -
McMicken Brady,
Thomas Robert J.,
Brancaleon Lorenzo
Publication year - 2014
Publication title -
journal of biophotonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 66
eISSN - 1864-0648
pISSN - 1864-063X
DOI - 10.1002/jbio.201300066
Subject(s) - porphyrin , chemistry , tubulin , photochemistry , conformational change , microtubule , biophysics , irradiation , fluorescence , stereochemistry , biology , physics , quantum mechanics , nuclear physics , microbiology and biotechnology
The irradiation of the complex formed by meso‐tetrakis (sulfonatophenyl) porphyrin (TSPP) and tubulin was investigated as well as its effects on the structure and function of the protein. We have used tubulin as a model target to investigate whether photoactive ligands docked to the protein can affect the structure and function of the protein upon exposure to visible light. We observed that laser irradiation prompts bleaching of the porphyrin which is accompanied by a sharp decrease (∼2 ns) in the average fluorescence lifetime of the protein and a change in the dichroic spectrum consistent with a decrease of helical structure. The result indicated the photoinduced partial unfolding of tubulin. We also observed that such partial conformational change inhibits the formation of microtubules in vitro . We investigated whether photosensitization of reactive oxygen species was responsible for these effects. Even upon removal of O 2 the protein still undergoes conformational changes indicating that irradiation of the bound porphyrin does not require the presence of O 2 to prompt conformational and functional effects opening the possibility that other mechanisms (e.g., charge transfer) are responsible for the photoinduced mechanism. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)