Haloacetonitriles are low K1 inhibitors of bacterial dichloromethane dehalogenases.

Distinct dichloromethane dehalogenases from Methylobacterium sp. strain DM4 and Methylophilus DM11 were inhibited by low concentrations of haloacetonitriles. Chloroacetonitrile (ClCH2CN) showed maximal inhibition at a stoichiometry of 1 mol inhibitor:1 mol holoenzyme for both enzymes. This stoichiometry is suggestive of one active site per holoenzyme or extreme negative cooperativity amongst the subunits. Radiolabelled ClCH2CN dissociated completely or partially from the two dehalogenases, respectively, during chromatography. This suggested ClCH2CN was bound non-covalently.