J. Iran. Chem. Soc., Vol. 7, No. 1 March 2010, pp.51~58.

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Quantum Chemical Analysis of ATP, GTP and Related Compounds in Gas Phase

A.H. Pakiaria,*, M. Farrokhniaa and A. Moradshahib

aDepartment of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran
bDepartment of Biology, College of Sciences, Shiraz University, Shiraz 71454, Iran

Adenosine 5'-triphosphate (ATP) and Guanine 5'-triphosphate (GTP), which are highly significant species for biological system as sources of energy, along with two other compounds, ribose 5'-triphosphate (RTP) and triposphate (TP), have been investigated theoretically. The capability of releasing terminal phosphoric acid and existent intramolecular bonds in their structure have been studied in gas phase. Due to the presence of hydrogen bonds in the above molecules, several inner and stable rings have been formed by atoms in molecules. The Quantum Theory of Atoms in Molecules (QTAIM) has been used in order to discover the intramolecular interactions properties in terms of charge densities. We have also demonstrated that the release of terminal phosphoric acid in ATP and GTP are both facilitated in the presence of ribose and base in comparison with TP and RTP. Our calculations have been done using density functional procedure.

Keywords: ATP, GTP, QTAIM, Intramolecular hydrogen bond

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