Structure-energy relations in methylcobalamin with and without bound axial base.
The properties of the Co-C bond in methylcobalamin (MeCbl) are analyzed by means of first-principles molecular dynamics. The optimized structure is in very good agreement with experiments, reproducing the bent-up deformation of the corrin ring as well as the metal-ligand bond distances. The analysis of the binding energies, bond orders, and vibrational stretching frequencies shows that the axial base slightly weakens the Co-C bond (by 4%), while the alkyl ligand substantially reinforces the Co-axial base bond (by 90%). These findings support several experiments and provide insight into the conversion between the base-on and base-off forms of the MeCbl cofactor.
Rovira
Carme
C
Centre de Recerca en Química Teorica, Parc Científic de Barcelona, Josep Samitier 1-5, 08028 Barcelona, Spain. crovira@pcb.ub.es
Biarnés
Xevi
X
Kunc
Karel
K
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003035:Cobalt / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000737:chemistry*
D008024:Ligands; D003035:Cobalt; C019476:mecobalamin; D014805:Vitamin B 12