Proton mediated spin state transition of cobalt heme analogs.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31127106.
- Also identified by DOI 10.1038/s41467-019-10357-z and PMC identifier 6534676.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The spin state transition from low spin to high spin upon substrate addition is one of the key steps in cytochrome P450 catalysis. External perturbations such as pH and hydrogen bonding can also trigger the spin state transition of hemes through deprotonated histidine (e.g. Cytochrome c). In this work, we report the isolated 2-methylimidazole Cobalt(II) [Co(TPP)(2-MeHIm)] and [Co(TTP)(2-MeHIm)], and the corresponding 2-methylimidazolate derivatives where the N-H proton of axial 2-MeHIm is removed. Interestingly, various spectroscopies including EPR and XAFS determine a high-spin state (S = 3/2) for the imidazolate derivatives, in contrast to the low-spin state (S = 1/2) of all known imidazole analogs. DFT assisted stereoelectronic investigations are applied to understand the metal-ligand interactions, which suggest that the dramatically displaced metal center allowing a promotion e<sub>g</sub>(d<sub>π</sub>) → b<sub>1g</sub>([Formula: see text]) is crucial for the occurrence of the spin state transition.
Medical subject headings
- Cobalt
- Heme
- Protons