Possible Origin for Porphin Derivatives in Prebiotic Chemistry – A Computational Study

Aylward, Nigel; Bofinger, Neville

doi:10.1007/s11084-005-2044-x

Cited by 25 publications

(27 citation statements)

References 26 publications

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“…The standard calculations at the HF and MP2 levels including zero-point energy corrections [13], together with scaling [14], using the same basis set, 6-31G*, are as previously published [5]. Enthalpy changes at the HF level not including scaled zero point energies are designated as ΔH.…”

Section: Problem Formulationmentioning

confidence: 99%

“…From a prebiotic perspective [5] it is desirable if the reactant molecules formed spontaneously from a supposed prebiotic atmosphere to be inevitably present. It has often been held that the atmosphere of the Earth was originally mildly reducing [2,6] implying the presence of concentrations of carbon monoxide, ammonia, water, hydrogen and hydrogen sulfide.…”

Section: Introductionmentioning

confidence: 99%

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A Prebiotic Surface Catalysed Photochemically Activated Synthesis of L-Cysteine

Aylward¹

2017

Proceedings of the 2016 International Conference on Biological Engineering and Pharmacy (BEP 2016)

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Abstract-Ethyne forms a weak charge-transfer complex with surface catalysts such as Mg.porphin in which the ethyne group has a net positive charge (0.08), and the conjugated porphin has a negative charge. This neutral complex is polarised and undergoes a nucleophilic addition reaction with ammonia at the carbene carbon to form Mg.2-amino ethenyl.porphin which has a tendency to the formation of cyclic Mg.1H aziridin-2yl.porphin complex. Nucleophilic attack by hydrosulfide anion ultimately yields a complex of bound 2-mercapto ethanimine. When the imine is bound to a Mg.porphin complex in which carbon monoxide has been oriented by exciting radiation an aziridine-2one complex is formed hydrolysable to the amino acid L-cysteine. The reactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the HF and MP2 /6-31G* level.

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Section: Problem Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Prebiotic Surface Catalysed Photochemically Activated Synthesis of L-Cysteine

Aylward¹

2017

Proceedings of the 2016 International Conference on Biological Engineering and Pharmacy (BEP 2016)

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“…In this regard, a prebiotically plausible route to tetrapyrrole molecules has yet to be demonstrated (Miller 1986(Miller , 1987(Miller , 1998, at least in the context of robust reaction of simple species in anaerobic aqueous solution to give measurable quantities of stable product. This dearth exists despite extensive studies in the half-century since Miller's seminal spark-discharge experiments (for a review of early work, see : Wnuk 1983; for more recent work, see : Scott 1997;Aylward and Bofinger 2005;Ksander et al 1987;Meierhenrich et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Simple Formation of an Abiotic Porphyrinogen in Aqueous Solution

Lindsey

Ptaszek

Taniguchi

2009

Orig Life Evol Biosph

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Porphyrins have long been proposed as key ingredients in the emergence of life yet plausible routes for forming their essential pyrrole precursor have heretofore not been identified. Here we show that the anaerobic reaction of δ-aminolevulinic acid (ALA, 1-5 mM) with the β-ketoester methyl 4-methoxyacetoacetate (2-40 mM) in water (pH5-7) at 70-100°C for >6 h affords the porphyrinogen, which upon chemical oxidation gives the corresponding porphyrin in overall yield of up to 10%. The key intermediate is the α-methoxymethyl-substituted pyrrole, which undergoes tetramerization and macrocycle formation under kinetic control. The resulting type-I porphyrin bears four propionic acid and four carbomethoxy groups, is distinct from porphyrins (e.g., uroporphyrin or coproporphyrin) derivable from ALA alone via the extant universal biosynthetic path to tetrapyrroles, and is photoactive upon assembly into cationic micelles in aqueous solution. The simple self-organization of eight acyclic molecules into a tetrapyrrole macrocycle, from which a porphyrin is derived that is photoactive in lipid assemblies, augurs well for the spontaneous origin of catalysts and pigments essential for prebiotic metabolism and proto-photosynthesis.

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“…[1,2] Interestingly, in current photosynthetic systems, this process relies on the formation of a carbamate as the first step of the cycle, [3] which may also have been the case in prebiotic systems, as a number of cyanide-based, nitrogen-rich, conjugated organic molecules, such as nucleic acids, porphyrins, and phthalocyanines, existed before life began. [4] In synthetic chemistry, numerous transition-metal catalysts for the activation of CO 2 have been explored. [5,6] Previous metal-free attempts concentrated on the use of alkylated amidines and guanidines, [7][8][9][10] such as 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU, 1, Scheme 1).…”

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confidence: 99%