The nature of the Co-C bond cleavage processes in methylcob(II)alamin and adenosylcob(III)alamin

Spataru Tudor; Fernandez Francisco

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2020-11-05 03:58

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542:577.16 (1)

Practical laboratory chemistry. Preparative and experimental chemistry (139)

Material bases of life. Biochemistry. Molecular biology. Biophysics (664)

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SPATARU, Tudor, FERNANDEZ, Francisco. The nature of the Co-C bond cleavage processes in methylcob(II)alamin and adenosylcob(III)alamin. In: Chemistry Journal of Moldova, 2016, nr. 1(11), pp. 10-20. ISSN 1857-1727. DOI: https://doi.org/10.19261/cjm.2016.11(1).01

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Chemistry Journal of Moldova

Numărul 1(11) / 2016 / ISSN 1857-1727 /ISSNe 2345-1688

The nature of the Co-C bond cleavage processes in methylcob(II)alamin and adenosylcob(III)alamin

DOI:https://doi.org/10.19261/cjm.2016.11(1).01

CZU: 542:577.16

Pag. 10-20

Spataru Tudor, Fernandez Francisco

Columbia University, New York

Disponibil în IBN: 11 iulie 2016

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Unfortunately, there are still signifi cant disagreements between experimental and theoretical data of rate constants, energy barriers for Co-C bond cleavage process and coordination numbers of vitamin B12 coenzyme species in spite of the remarkable efforts done by research community. Therefore, no grounded mechanisms for Co-C vitamin B12 coenzyme bond breaking process and subsequent reactions have been found up to now. The infl uence of the mixing orbitals e.g. Pseudo-Jahn-Teller and similar effects on the reactions paths of bond-cleavage mechanisms of vitamin B12 co-factors must be taken into account by utilizing multi-reference methods, in particular multiconfi gurational self-consistent fi eld (MCSCF) method. Then, the change in total energy along the normal coordinate Q for the stretching mode including Co-C and Co-N bonds in vitamin B12 cofactors is expected due to a “vibronic” coupling term, which couples an excited state and ground state by a second order derivative potential-energy operator. The strong state mixing effect is expected to lead to low energy barriers and to Co-C and Co-N axial bond cleavage events in agreement with experimental data. Afterward, the updated mechanisms of vitamin B12 bio-processes can be determined.

Cuvinte-cheie
vitamin B12, Mechanism, Pseudo-Jahn-Teller effect, DFT,

bio-catalysis, MCSCF

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