Formamide and the origin of life

Abstract

The complexity of life boils down to the definition: "self-sustained chemical system capable of undergoing Darwinian evolution" (Joyce, 1994) [1]. The term "self-sustained" implies a set of chemical reactions capable of harnessing energy from the environment, using it to carry out programmed anabolic and catabolic functions. We briefly present our opinion on the general validity of this definition.Running anabolic and catabolic functions entails complex chemical information whose stability, reproducibility and evolution constitute the core of what is dubbed genetics.Life as-we-know-it is made of the intimate interaction of metabolism and genetics, both built around the chemistry of the most common elements of the Universe (hydrogen, oxygen, nitrogen, carbon). Other elements like phosphorus and sulphur play important but ancillary and potentially replaceable roles.The reproducible interaction of metabolic and genetic cycles results in the hypercycles of organization and de-organization of chemical information that we consider living entities. In order to approach the problem of the origin of life it is therefore reasonable to start from the assumption that both metabolism and genetics had a common origin, shared a common chemical frame, were embedded in physical-chemical conditions favourable for the onset of both.The most abundant three-atoms organic compound in interstellar environment is hydrogen cyanide HCN, the most abundant three-atoms inorganic compound is water H 2 O. The combination of the two results in the formation of formamide H 2 NCOH. We have explored the chemistry of formamide in conditions compatible with the synthesis and the stability of compounds of potential pre-genetic and pre-metabolic interest. We discuss evidence showing (i) that all the compounds necessary for the build-up of nucleic acids are easily obtained abiotically, (ii) that essentially all the steps leading to the spontaneous generation of RNA are abiotically possible, (iii) that the key compounds of extant metabolic cycles are obtained in the same chemical frame, often in the same test tube.How close are these observations to a plausible scenario for the origin of life?

Some Insights Into Formamide Formation Through Gas-Phase Reactions in the Interstellar Medium

“…This makes it reactive at both amino and carbonyl sites and it could play a key role in the origin of life (Saladino et al 2012). Several formation schemes of formamide in space have been proposed on ice of interstellar grains or in the gas phase.…”

Impact synthesis of the RNA bases

“…Astronomers have recently reported its presence in our solar system found within the atmospheres of comets (6), and since the 1970s, formamide has been detected in multiple regions in the interstellar medium (7). The known chemistry and ubiquity of formamide has made it an attractive primordial feedstock compound for the production of many prebiotic molecules (8). Experiments on the prebiotic synthesis of nucleobases using formamide have Simulated impact or shock synthesis of organic compounds has remained a plausible model for the production of organic compounds needed for prebiotic chemistry.…”

“…However, these studies were important because they demonstrated that formamide could be a common feedstock for each RNA base. What remained was the task of finding plausible conditions that could access all of the bases in one experiment (8).…”

“…Ferus et al go on to show how using a negative control, the likely role of the clay is the adsorption of cytosine to the mineral surface (19), which limited its hydrolytic degradation. The use of minerals to catalyze reactions of formamide is well documented (8), but the preservation of a labile nucleobase under these highly energetic conditions may provide a scenario for the prebiotic accumulation of cytosine.…”

“…In recent years the use of formamide as a reagent and solvent has garnered many proponents in the origin-of-life research community (8,20). The work by Ferus et al (5) provides an intriguing example for how the chemistry of formamide is being used to address some of the underlying problems that have persisted in the field.…”