WSEAS Transactions on Biology and Biomedicine
Print ISSN: 1109-9518, E-ISSN: 2224-2902
Volume 15, 2018
A Prebiotic Surface Catalyzed Photochemically Activated Synthesis of Vitamin B12
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Abstract: The four stereospecific pyrroline derivatives present in the corrin structure of Vitamin B12 may be oligomerized to form a corrin structure or a porphin structure. The analogous porphin structure is formed with a lower activation energy and favourable free energy change. The corresponding corrin structure requires a greater activation energy and gives a less favourable free energy change. The resulting corrin structure may then chelate a metal ion and accept a propyne adduct in a stereospecific manner which subsequently binds metaphosphoric acid. The charge transfer adduct is cleaved by the partially hydrolyzed cyanopropyne substituent of ring D. The corrin structure is then free to bind five carbon monoxide molecules to form aziridin-2one adducts. These can be photochemically activated to form the α-D-ribose and add a hydrogen ion. A carbonyl reaction site is then available to bond with the rare 5,6-dimethyl benzimidazole base. Further hydrogenation frees the sugar and rotation allows the bonding of the rare base to the metal ion. 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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Pages: 68-80
WSEAS Transactions on Biology and Biomedicine, ISSN / E-ISSN: 1109-9518 / 2224-2902, Volume 15, 2018, Art. #8