Stabilizing intramolecular cobalt–imidazole coordination with a remote methyl group in the backbone of a cofactor B12–protein model
This communication describes the stabilizing effect (ΔΔG° = −4 kJ mol−1) of a remote methyl group in the backbone of a cobalamin–enzyme mimic on intramolecular imidazole–cobalt coordination. For this purpose, two B12 derivatives with an appended imidazole base were synthesized and analysed with spectrophotometric pH titrations. Qualitative conformation analysis of the backbone structure suggests that a thermodynamically unfavoured gauche interaction in the base-off form of a model containing an (R)-configured CH3 group at position C176 of the linker between the corrin ring and the terminal imidazole ligand steers the base toward cobalt coordination.
- This article is part of the themed collection: New Talent: Europe