NADH-Dependent Halogenases Are More Likely To Be Involved in Halometabolite Biosynthesis Than Haloperoxidases

摘要

The detection of chloroperoxidase from the fungus Caldari-omyees fumago and the development of a simple spectropho-tometric assay for the detection of halogenating enzymesbased on the synthetic compound mono-chlorodimedone as organic substrate resulted in the subsequent isolation of a number of haloperoxidases from different organisms. All these enzymes produce hypohalogenic acid, which is the actual halogenating agent. Thus, halogenation catalvzed by haloperoxidases lacks substrate and regiospecificity. However, investigations of the biosynthetic pathways of different halometabolites have shown that biological halogenation must be specific. Furthermore, the formation offluorinated metabolites by haloperoxidases is difficult to explain, as fluoride cannot be oxidized in the haloperoxidase reaction.