two enzymes , one an acetylmorphine carboxyesterase , the other a morphine dehydrogenase , have been isolated from bacteria . the amce degrades heroin to morphine and the mdh oxidizes morphine to morphinone , with the aid of a cofactor . more particularly , the invention pertains to a process for preparing a 6 - ketone from morphine or a methyl or ethyl derivative thereof . the process comprises oxidizing morphine or an ether derivative in the presence of a morphine dehydrogenase and the cofactor nadp + . these reactions are used in detection of heroin or morphine . the enzymes can be incorporated in sensors for this purpose .