Our work is directed toward protein structure-function relationships, with special emphasis on enzyme activation mechanisms. One project involves mechanistic studies on chloroperoxidase and related halogenating enzymes which catalyze iodination, bromination, chlorination, and hydroxylation reactions. We have discovered a new enzyme, methyl chloride transferase, which catalyzes the synthesis of methyl chloride from S-adenosyl methionine and chloride ion.
Many halophytic plants are rich sources of the enzyme.
We are currently examining the metabolic role of methyl chloride transferase in halophytic plant metabolism. Our working hypothesis is that the transferase serves to regulate internal chloride ion concentrations by producing a volatile chlorine product. Seven hundred base pairs have been sequenced upstream from the structural gene and experiments are in progress to identify the promoter region. Recent investigations on the mechanisms of the halogenation reaction catalyzed by chloroperoxidase has revealed that it is related to the P 450 cytochromes, horseradish peroxidase and catalase. Studies involving site-specific mutagenesis of the structural gene for chloroperoxidase are now underway, and we believe that what we learn will tie together a lot of the chemistry in the heme containing proteins.