We have identified proteolytic activity in whole body extracts of whiteflies. We have demonstrated enzymatic activity at pH 5.5, but not at neutral pH, and have shown the absence of inhibition with several trypsin and chymotrypsin inhibitors. Thus, we suspected that the observed enzymatic activity was cysteine proteinase-like. Using a spectrophotometric assay with a synthetic cysteine protease substrate, N,a-benzoyl-DL-arginine-2-naphthylamide, we detected high levels of activity at pH 5.6 in whole-body whitefly extracts. However, we have, thus far, been unable to establish first-order enzyme kinetics over time. We suspect that this is possibly due to the presence of inhibitors in whitefly hemolymph. Recently, we have identified the native protein(s) involved in the cysteine protease activity in whole-body whitefly extracts using a native gelatin/PAGE assay. Future studies will focus on further characterization of the whitefly cysteine protease and localization of the enzyme activity to specific tissues and/or cell types.
Species 1: Hemiptera Aleyrodidae Bemisia tabaci (silverleaf whitefly, sweetpotato whitefly)
Keywords: digestive enzyme, proteolytic activity
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