Dehalogenase: the Follow-up Enzyme after Mustard Oxidation

Sulfur mustard (HD) has been used as a chemical warfare agent since 1917. Currently fielded M258A1 and M280 decontamination kits and prospective oxidative decontaminants convert HD to HD sulfoxide (HDSO). Although, the latter is not considered a vesicant, it is highly recalcitrant and its systemic toxicity, reportedly, is comparable to the agent. We found that live cells of a known hexachlorocyclohexane (lindane) metabolizing Sphingomonas paucimobilis bacterium could degrade HDSO. Cell free crude extract was obtained and found capable of HDSO enzymatic dehalogenation. Dehalogenase activity was monitored by determining chloride release using the Iwasaki colorimetric method. The reaction was also monitored by using GC-FPD and GC-ECD on derivatized samples. These results demonstrate the potential use of S. paucimobilis derived enzyme(s) in furthering the destruction of HD agent, thus providing significant contribution to the “Green” solution of the decontamination problem. This could be an important factor for the US and other nations in attempting to meet the requirements of 1993 Chemical Weapons Convention to destroy all chemical warfare agents within ten years of ratification (April 2007 for the US).