Title
Spectroscopic study on the binding of chelerythrine with duplex poly (rA): A model of RNA intercalation
Author
Ankur Bikash Pradhan, Sutanwi Bhuiya, Lucy Haque, Suman Das
Year
2017
Journal
International Journal of Biological Macromolecules
Abstract
Here we have reported a detail study on the interaction of the benzophenanthridine alkaloid chelerythrine (CHL) with double stranded polyriboadenylic acid [ds poly (rA)] by exploiting various spectroscopic techniques. The alkaloid shows high binding affinity (binding constant is 1.10 × 105 M−1) towards the double stranded RNA as revealed from Scatchard plot. The binding was confirmed by hypochromic effect in the UV–vis spectrum of CHL, increase in fluorescence intensity of CHL and perturbations of the circular dichroism (CD) spectrum of ds poly (rA). Later fluorescence quenching, cooperative CD melting transition, viscometric and molecular modeling studies establish the fact that the alkaloid binds to the ds poly (rA) by the mechanism of intercalation. Thermodynamic parameters obtained from the isothermal titration calorimetric (ITC) study show that the binding is favoured by negative enthalpy and small positive entropy changes. This report may be a model for intercalation of small molecule like CHL to the double stranded RNA.
Instrument
J-815
Keywords
Circular dichroism, RNA structure, Ligand binding, Thermal stability, Thermodynamics, Biochemistry