Reversible Protonation of a Thiolate Ligand in an [Fe]-Hydrogenase Model Complex

Reversible Protonation of a Thiolate Ligand in an [Fe]-Hydrogenase Model Complex:

What is the channel? The thiolate ligand in the five-coordinate model complex 1 of [Fe]-hydrogenase is preferentially and reversibly protonated, even in the presence of an acyl ligand. The results suggest that the Cys176 thiolate ligand in [Fe]-hydrogenase can serve as the internal base to accept the proton after heterolytic splitting of H₂.