Amino acid composition of the highly purified allergen from Dirofilaria immitis.

The amino acid analysis of the purified allergen from Dirofilaria immitis revealed that it had a total number of 98 amino acid residues. The allergen was remarkably rich on glutamic acid (15 residues), lysine (14 residues) and aspartic acid (12 residues). No half-cystine was obtained. The ratio of the acidic residues to the basic ones was 1.4. The weak positive charge of the allergen is contributed by the fewer number of basic residues relative to acidic residues.