期刊
ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES
卷 39, 期 6, 页码 495-515出版社
SPRINGER
DOI: 10.1007/s11084-009-9168-3
关键词
Prebiotic; Pyrrole; Porphyrinogen; Porphyrin; Self-assembly; Micelle; Photosynthesis
类别
资金
- North Carolina State University
- NCSU Department of Chemistry Mass Spectrometry Facility
- North Carolina Biotechnology Center
- NCSU Department of Chemistry
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 delta-aminolevulinic acid (ALA, 1-5 mM) with the beta-ketoester methyl 4-methoxyacetoacetate (2-40 mM) in water (pH 5-7) at 70-100A degrees 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 alpha-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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