ibn-ResPubl-45617
2016-06-22
11
1
10
1857-1727
https://ibn.idsi.md/ro/vizualizare_articol/45617
The nature of the Co-C bond cleavage processes in methylcob(II)alamin and adenosylcob(III)alamin
vitamin B12; Mechanism; bio-catalysis; Pseudo-Jahn-Teller effect; DFT; MCSCF
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.
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2016-06-22T24:00:00
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2016-06-22T24:00:00
ibn-person-19043
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2016-06-22T24:00:00
ibn-person-48262
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2016-06-22T24:00:00
ibn-doi-45617
10.19261/cjm.2016.11(1).01
2016-06-22T24:00:00
31d222b4-11e0-434b-b5ae-088119c51189
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5123451
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2016-06-22T24:00:00
Spataru
Tudor
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2016-06-22T24:00:00
Fernandez
Francisco
5123451
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