Quantum chemical analysis of ATP, GTP and related compounds in gas phase

Adenosine 5'-triphosphate (ATP), an adenine nucleotide, is extremely important to metabolism because it is currency of energy exchange in metabolic process. ATP stores free energy in its two phosphoanhydrid bonds and transfers this energy when it is hydrolyzed to adenosine 5'-diphosphate and orthophosphate (P) or adenosine 5'-monophosphate and pyrophosphate.1 ATP, ADP and AMP are made up of three units: an adenine, a ribose and one phosphate groups. These molecules involved in a vast variety of chemical environments and applications from inorganic to biological systems.[2,3] Guanosine 5'-triphosphate (GTP) is a similar molecule to ATP and the chemical energy derived from the hydrolysis of P-O-P linkage of guanine di- and triphosphate (i.e. GDP and GTP) is used by the cells to carry out different biological functions as ATP.[4] In the present article, we have made a question about biological superiority of ATP in living systems. Our primary aim is to find roles of adenine and ribose in ATP molecule. Due to attention this, properties of terminal P-O bond have been studied in three molecules that all are in common in their pyrophosphate tails but differ in parts involving adenine and ribose. Finally effects of ribose and other organic nucleobase, guanine have been considered in other similar molecule, GTP, and the results were in good agreement with those obtained from ATP.