Non-covalent binding of the heavy atom compound [Au(CN)2]- at the halide binding site of haloalkane dehalogenase from Xanthobacter autotrophicus GJ10.

The Na[Au(CN)2] heavy atom derivative contributed considerably to the successful elucidation of the crystal structure of haloalkane dehalogenase isolated from Xanthobacter autotrophicus GJ10. The gold cyanide was located in an internal cavity of the enzyme, which also contains the catalytic residues. Refinement of the dehalogenase-gold cyanide complex at 0.25 nm to an R-factor of 16.7% demonstrates that the heavy atom molecule binds non-covalently between two tryptophan residues pointing into the active site cavity. At this same site also chloride ions can be bound. Therefore, inhibition of dehalogenase activity by the Au(CN)-2 presumably occurs by competition for the same binding site as substrates.