TRYPSIN-LIKE PROTEASE OF MITES - PURIFICATION AND CHARACTERIZATION OFTRYPSIN-LIKE PROTEASE FROM MITE FECAL EXTRACT DERMATOPHAGOIDES-FARINAE - RELATIONSHIP BETWEEN TRYPSIN-LIKE PROTEASE AND DER-F-III

A serine protease from mite faecal extract, Dermatophagoides farinae, was purified using DEAE-Sephacel anion exchange chromatography and Sup erdex 75 pg gel chromatography. The molecular weight of this protease was 34 kD on SDS-PAGE under reducing conditions. The optimal pH and te mperature of the protease were 8.0 and 47-degrees-C, respectively. In addition, this protease cleaved arginyl or lysyl residue containing su bstrates selectively and was only inhibited by aprotinin, FUT-175, and soy bean trypsin inhibitor and not by chymostatin, E-64 and iodoaceti c acid. These results show that our purified serine protease belongs t o the trypsin-type. Purified trypsin-like protease was shown to be all ergenic by enzyme-linked immunosorbent assay. Antigenicity of trypsin- like protease was completely different from those of Der f I and Der f II. Both, 20 N-terminal amino acid sequence and amino acid compositio ns of the purified protease were very similar to those of Der f III. G ood similarities were found between trypsin-like protease and Der f II I concerning physicochemical properties such as molecular weight on SD S-PAGE and ammonium sulphate solubility. Summarizing the above data, i t can be concluded that a trypsin-like protease from mite faecal extra ct is actually the Der f III allergen and that it may be involved in t he digestive process of the mite as it was found not in mite body but in mite faeces.