Prebiotic Precursors of the Primordial RNA World in Space: Detection of NH₂OH

Abstract

One of the proposed scenarios for the origin of life is the primordial RNA world, which considers that RNA molecules were likely responsible for the storage of genetic information and the catalysis of biochemical reactions in primitive cells, before the advent of proteins and DNA. In the last decade, experiments in the field of prebiotic chemistry have shown that RNA nucleotides can be synthesized from relatively simple molecular precursors, most of which have been found in space. An important exception is hydroxylamine, NH2OH, which, despite several observational attempts, it has not been detected in space yet. Here we present the first detection of NH2OH in the interstellar medium toward the quiescent molecular cloud G+0.693-0.027 located in the Galactic Center. We have targeted the three groups of transitions from the J = 2−1, 3−2, and 4−3 rotational lines, detecting five transitions that are unblended or only slightly blended. The derived molecular abundance of NH2OH is (2.1 ± 0.9) × 10−10. From the comparison of the derived abundance of NH2OH and chemically related species, with those predicted by chemical models and measured in laboratory experiments, we favor the formation of NH2OH in the interstellar medium via hydrogenation of NO on dust grain surfaces, with possibly a contribution of ice-mantle NH3 oxidation processes. Further laboratory studies and quantum chemical calculations are needed to completely rule out the formation of NH2OH in the gas phase.

Discovery in space of ethanolamine, the simplest phospholipid head group

“…2 . This region is one of the most chemically rich reservoirs of molecules in the galaxy, with a plethora of organic species detected ( 21 – 25 ). The extremely rich gas-phase chemical composition of this region is due to erosion of the ice mantles of interstellar dust grains by large-scale low-velocity ( 20 km ) shocks ( 26 ) induced by a collision between massive molecular clouds ( 27 ).…”

“…The prebiotic availability of ethanolamine on early Earth could have triggered the formation of efficient and permeable amphiphilic molecules such as phospholipids, thus playing a relevant role in the evolution of the first cellular membranes needed for the emergence of life. most chemically rich reservoirs of molecules in the galaxy, with a plethora of organic species detected (21)(22)(23)(24)(25). The extremely rich gas-phase chemical composition of this region is due to erosion of the ice mantles of interstellar dust grains by large-scale lowvelocity (<20 km•s −1 ) shocks (26) induced by a collision between massive molecular clouds (27).…”

Photolysis of acetonitrile in a water-rich ice as a source of complex organic molecules: CH3CN and H2O:CH3CN ices

“…The mass peak at m/z = 33 is due to species with an elemental composition of NH 3 O. The molecular ion of hydroxylamine (NH 2 OH) could be a carrier of this signal, as is the case for (Fedoseev et al 2012) and was recently detected in space (Rivilla et al 2020).…”

Millimeter- and submillimeter-wave spectrum of trans-formaldoxime (CH2NOH)

“…The following isomers in relative thermodynamic stability are the tautomer C-hydroxymethanimine (Methanimidic acid, HN− −CHOH), which is 13.4 kcal/mol less stable than formamide, and formaldoxime (CH 2 NOH), which is 51.0 kcal/mol less stable than formamide (Lattelais et al 2010). The observation of methanimine, a reduced form of formaldoxime in the molecular cloud Sgr B2 (Godfrey et al 1973), and the recent detection of hydroxylamine, H 2 NOH, in the quiescent molecular cloud G+0.693-0.027 located in the Galactic Center (Rivilla et al 2020) prompted us to study formaldoxime. Methanimine is possibly synthesized in the ISM by the reaction of formaldehyde with ammonia (Vinogradoff et al 2011), while the reaction of formaldehyde with hydroxylamine could form formaldoxime.…”