Abiotic synthesis of ATP from AMP in the gas phase: implications for the origin of biologically important molecules from small molecular clusters

Abstract

In spite of decades of research, little is known about the processes leading to the prebiotic formation of some of the key molecular components involved in the origin of life. We have undertaken a systematic investigation of small noncovalent clusters in the gas phase, using collisional activation to effect reactions between the cluster components, with the goal of identifying processes that lead to the production of chemical species which may have been key players at the threshold of life. Here, we report that collisional activation of a trimer of adenosine 5′-monophosphate (AMP) leads exclusively to formation of the important species adenosine 5′-triphosphate (ATP). The AMP trimer can be either cationic or anionic with each AMP present as the sodium salt. An additional sodium ion yields the cationic cluster, while the anionic cluster lacks one sodium ion. The energetics of this reaction are explored using PM5 semi-empirical calculations and density functional theory. The generation of polyphosphate bonds is not exclusive to the AMP trimer. Sodiated clusters of other nucleotides, ribose phosphate, or phosphate itself lead to the generation of other biologically important polyphosphates. The implications of this chemistry for chemical and biological evolution are discussed.