Structural studies on the allergen Der p1 from the house dust mite Dermatophagoides pteronyssinus: similarity with cysteine proteinases.

A major allergen (Der p1) has been purified to homogeneity from faecal particles from the house dust mite Dermatophagoides pteronyssinus. Reversed-phase microbore HPLC was employed to fractionate and purify a number of tryptic peptides generated from approximately 20 nmol of purified Der p1. N-Terminal amino acid sequence analyses were performed on the intact polypeptide and six tryptic peptides yielding 89 unique assignments; this corresponds to 40% of the molecule. These data are compared with the cDNA-deduced amino acid sequence of the Der p1 allergen. There is extensive similarity between the N-terminal amino acid sequence of Der p1 and the cysteine proteases actinidin and papain. A low Mr protein (approximately 17,000) was resolved from S-carboxymethyl Der p1 by gel-permeation chromatography. Edman degradation of the first 24 residues of this material revealed no similarity with Der p1. It is not clear whether this component is a low Mr disulfide-linked chain derived from Der p1 or represents an unidentified mite component.