Cobalt sulfur-bond cleavage

The peptide bond that is cleaved is the bond between Leu-189 and Asp-190. There are two peptide bonds in close proximity to the iron chelate on Cys-212. The other peptide bond is between He-144 and Gly-145. The Cys-212 sulfur is 5.1 A from the carbonyl carbon of Gly-145, and 5.3 A from the carbonyl carbon of Leu-189. However, the main difference is that the peptide bond of Leu-189-Asp-190 is oriented parallel to Cys-212, while the peptide bond of lie-144-Gly-145 is oriented away for Cys-212. As was seen with cobalt(lll) hydrolysis of peptide bonds, the proximity and orientation of the carbonyl carbon is important for hydrolysis. This approach has been extended to the cleavage of multisubunit proteins. Palladium(n) and platinum(ll) complexes as synthetic peptidases have been reviewed elsewhere. ... 

The promotion effect of the CoMoS site appears to occur through increased hydrogen activation, which facilitates removal of sulfur atoms after cleavage of C-S bonds on exposed molybdenum ions/ Cobalt incorporated into the support may also act as a structural promoter by enhancing dispersion of the sulfided species. ... 

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