Stabilizing intramolecular cobalt-imidazole coordination with a remote methyl group in the backbone of a cofactor B 12 -protein model

• Published in: Dalton transactions : an international journal of inorganic chemistry 2018-08, Vol.47 (31), p.10443-10446
• Main Authors: Sonnay, Marjorie, Zelder, Felix
• Format: Article
• Language: English
• Subjects: 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase - chemistry; Biomimetics; Catalytic Domain; Cobalt - chemistry; Coordination Complexes - chemical synthesis; Coordination Complexes - chemistry; Humans; Imidazoles - chemistry; Ligands; Molecular Structure; Thermodynamics; Vitamin B 12 - analogs & derivatives; Vitamin B 12 - chemical synthesis; Vitamin B 12 - chemistry
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt01298a

This communication describes the stabilizing effect (ΔΔG° = -4 kJ mol ) of a remote methyl group in the backbone of a cobalamin-enzyme mimic on intramolecular imidazole-cobalt coordination. For this purpose, two B 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 CH group at position C176 of the linker between the corrin ring and the terminal imidazole ligand steers the base toward cobalt coordination.