Tryptophan residue is essential for immunoreactivity of a diagnostically relevant peptide epitope of A. fumigatus.

The role of tryptophan (Trp17) in immunoreactivity of P1, the diagnostically relevant peptide from a major allergen/antigen of Aspergillus fumigatus, was evaluated by chemically modifying tryptophanyl residue of P1. In BIAcore kinetic studies, unmodified P1 showed a 100-fold higher binding with ABPA (Allergic Bronchopulmonary Aspergillosis) patients' IgG [KD (equilibrium dissociation constant) = 2.74 e(-8) +/- 0.