Our laboratory investigates proteins from the hemolymph (blood) of insects, with special interest in the proteins' functions in the insect immune system. We are studying plasma proteins involved in the melanization cascade, which is activated in response to infection. This system includes prophenoloxidase, serine proteases, protease inhibitors from the serpin superfamily, and proteins that bind to microbial polysaccharides. We also study proteins present in hemocytes, using monoclonal antibodies and biochemical and molecular biological approaches. The long range goal is to understand the biochemical and cellular processes by which insect immune systems recognize and respond to pathogens and parasites.
We also investigate the biochemistry of cuticle protein cross-linking, which is responsible for the unique physical properties of insect exoskeletons. We want to understand the structure and function of cuticular proteins and the chemistry that occurs in the sclerotization process, when newly formed cuticle tans and hardens after an insect molts. Sclerotization involves oxidation of catechols, which then polymerize or react with proteins to form cross-links. We study enzymes involved in catechol synthesis and enzymes called laccases, which oxidize catechols. We are also examining potential functions of insect laccases that are not associated with cuticle sclerotization.