# Stability of the H-cluster under whole-cell conditions-formation of an H-like state and its reactivity towards oxygen.
> 全細胞条件下におけるHクラスターの安定性：H様状態の形成と酸素に対する反応性


## Abstract

The [FeFe]-hydrogenase enzyme catalyzes reversible H2 oxidation using a hexanuclear iron cofactor known as the H-cluster, which exhibits exceptional catalytic performance but is highly sensitive to oxygen. Under in vitro conditions, oxygen-stable H-cluster forms can be generated through sulfide treatment under oxidizing conditions. This study demonstrates that an H-like species arises spontaneously within intact cells over a period of hours, coinciding with cessation of H2 production. Supplementation with cysteine or sulfide during enzyme maturation accelerates formation of this H-cluster state. Furthermore, both steric factors and proton transfer pathways were found to influence the formation of the H-like species, highlighting the significance of outer coordination sphere interactions in governing H-cluster reactivity.

### Mechanism

An H-like state of the H-cluster forms spontaneously under intracellular conditions; its reactivity is governed by steric factors and outer coordination sphere proton transfer, with cysteine or sulfide promoting this transition.

## Bibliographic

- **Authors**: Lorenzi M, Ceccaldi P, Rodríguez-Maciá P, Redman HJ, Zamader A, Birrell JA, et al.
- **Journal**: J Biol Inorg Chem
- **Year**: 2022
- **PMID**: [35258679](https://pubmed.ncbi.nlm.nih.gov/35258679/)
- **DOI**: [10.1007/s00775-022-01928-5](https://doi.org/10.1007/s00775-022-01928-5)
- **PMC**: [PMC8960641](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8960641/)
- **Study type**: in vitro study
- **Delivery route**: in vitro
- **Effect reported**: not assessed

## Delivery context

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 35258679. https://h2-papers.org/en/papers/35258679
> **Source**: PubMed PMID [35258679](https://pubmed.ncbi.nlm.nih.gov/35258679/)