Crystallographic analysis of the catalytic mechanism of haloalkane dehalogenase

Nature. 1993 Jun 24;363(6431):693-8. doi: 10.1038/363693a0.


Crystal structures of haloalkane dehalogenase were determined in the presence of the substrate 1,2-dichloroethane. At pH 5 and 4 degrees C, substrate is bound in the active site without being converted; warming to room temperature causes the substrate's carbon-chlorine bond to be broken, producing a chloride ion with concomitant alkylation of the active-site residue Asp124. At pH 6 and room temperature the alkylated enzyme is hydrolysed by a water molecule activated by the His289-Asp260 pair in the active site. These results show that catalysis by the dehalogenase proceeds by a two-step mechanism involving an ester intermediate covalently bound at Asp124.

MeSH terms

  • Catalysis
  • Cloning, Molecular
  • Computer Simulation
  • Ethylene Dichlorides / metabolism
  • Gram-Negative Aerobic Bacteria / enzymology
  • Gram-Negative Aerobic Bacteria / genetics
  • Hydrogen-Ion Concentration
  • Hydrolases / chemistry
  • Hydrolases / genetics
  • Hydrolases / metabolism*
  • Hydrolysis
  • Temperature
  • X-Ray Diffraction


  • Ethylene Dichlorides
  • ethylene dichloride
  • Hydrolases
  • haloalkane dehalogenase