Figure 1: Proposed initial steps in the catalytic mechanism of RDases.
From: Cobamide-mediated enzymatic reductive dehalogenation via long-range electron transfer
(1) Alkylation of the cobalt by a nucleophilic attack of [CoI] on the carbon backbone of the organohalide. (2) Formation of a cobalt–halogen bond after [CoI] attack directly at the halogen substituent followed by heterolytic cleavage of the carbon–halogen bond. (3) Long-range electron transfer from [CoI] leading to substrate radical formation and finally to the formation of a carbanion after elimination of the halogen substituent (the elimination is not shown). [CoI–III]: oxidation states of the cobalt ion in the cobamide cofactor; R: hydrocarbon backbone; X: halogen substituent.
