Book of Abstracts: Albany 2009
June 16-20 2009
© Adenine Press (2008)
Uncovering Subtle Effects on Structures of Nucleic Acids in Solution and Protein-bound Forms Through Vibrational Spectroscopy
Nucleobase structures in solution are difficult to determine due to the possible existence of many tautomeric forms and protonation states. Determination of the precise solution state structures is important to understand the several protein-nucleic acid interactions that are central to cellular function. Vibrational spectra can provide valuable information beyond that obtained from crystal structures alone because of higher sensitivity of the spectra to hydrogen bonding and non-covalent interactions. We have exploited the potential of vibrational spectra to determine the solution and protein-bound structures of nucleic acids viz. hypoxanthine, xanthine, guanine and their corresponding nucleotides in solution and bound to protein. Ultraviolet resonance Raman spectroscopy was used to specifically obtain spectra from the nucleic acids without interference from the solution or protein environment. To further understand the effect of environment quantitatively, we have employed high-level ab intio and density functional theoretical calculations. I will demonstrate from our results that this combination of experimental and computational techniques provides unprecedented, detailed information on nucleic acids. We have used this combination of techniques to understand the differences in the binding of nucleotides to the human and P. falciparum enzyme, hypoxanthine guanine phosphoribosyl transferase (HGPRT). Our data show that subtle interactions of the ring substituents with the enzyme can explain the differences in the binding of hypoxanthine and guanine.
1National Centre for Biological Sciences, GKVK Campus,