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A Proteoliposome-Based Efflux Assay to Determine Single-molecule Properties of Cl- Channels and Transporters
Published on: April 20, 2015
Interaction of a potential chloride channel blocker with a model transport protein: a spectroscopic and molecular
Aniruddha Ganguly1, Bijan Kumar Paul, Soumen Ghosh
1Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Calcutta-700009, India. nguchhait@yahoo.com.
Abstract:
The present work demonstrates a detailed characterization of the interaction of a potential chloride channel blocker, 9-methyl anthroate (9-MA), with a model transport protein, Bovine Serum Albumin (BSA). The modulated photophysical properties of the emissive drug molecule within the microheterogeneous bio-environment of the protein have been exploited spectroscopically to monitor the probe-protein binding interaction. Apart from evaluating the binding constant, the probable location of the neutral molecule within the protein cavity (subdomain IB) is explored by an AutoDock-based blind docking simulation. The absence of the Red-Edge Effect has been corroborated by the enhanced lifetime of the probe, being substantially greater than the solvent reorientation time. A dip-and-rise characteristic of the rotational relaxation profile of the drug within the protein has been argued to originate from a significant difference in the lifetime as well as amplitude of the free and protein-bound drug molecule. Unfolding of the protein in the presence of the drug molecule has been probed by the decrease of the α-helical content, obtained via circular dichroism (CD) spectroscopy, which is also supported by the gradual loss of the esterase activity of the protein in the presence of the drug molecule.
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