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Spiders capture insects using a web net. The fact that they eat them without chewing suggests that spiders possess highly efficient digestive enzymes. Preliminary experiments indicated that a spider protease is able to digest synthetic spider dragline amyloid fibers. Thus, the spider protease has the potential ability to digest amyloid fibrils including pathogenic b-amyloid, such as amyloid fibrils, which are responsible for Alzheimer's disease. Therefore, we extracted and characterized the enzymes derived from Nephila Clavata. Spider saliva including proteolytic enzymes was prepared from Nephila Clavata by electrical stimulation. The extracts were applied to SDS-PAGE and the enzymatic activity of spider proteases was estimated by a casein protease assay. Two protein bands, showing protease activity, were predominantly observed on the assay and their molecular weights were estimated as approximately 21.9 and 19.5 kDa, based on the SDS-PAGE analysis. In order to characterize the enzymes, an inhibition assay for a synthetic peptide substrate was performed using several types of inhibitors, such as PMSF and EDTA. The results suggested that the spider protease can be categorized as a metal-dependent carboxypeptidease although the inhibitors were not able to completely depress the protease activity of the enzyme. The results will be discussed in this paper.

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