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) +/- 0.13 M] than the controls' IgG (KD = 2.97 e(-6) +/- 0.14 M), whereas chemically-modified P1 showed similar binding [KD patients' IgG = 3.25 e(-7) +/- 0.16 M, KD controls' IgG = 3.86 e(-7) +/- 0.19 M] indicating loss of specific immunoreactivity of P1 on tryptophan modification. Modified P1 showed loss of specific binding to IgE and IgG antibodies of ABPA patients in ELISA (Enzyme-Linked Immunosorbent Assay). The study infers that tryptophan residue (Trp17) is essential for immunoreactivity of P1.
Kamal
Neel
N
Institute of Genomics and Integrative Biology, Mall Road, Delhi, India.
Chowdhury
Shantanu
S
Madan
Taruna
T
Sharma
Deepak
D
Attreyi
M
M
Haq
Wahajul
W
Katti
Seturam Bandacharya
SB
Kumar
Anil
A
Sarma
P Usha
PU
D001229:Aspergillosis, Allergic Bronchopulmonary / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D001232:Aspergillus fumigatus / Q000276:immunology*; D019149:Bioreactors / Q000382:microbiology; D016022:Case-Control Studies; D002942:Circular Dichroism; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007700:Kinetics; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000276:immunology*; D012997:Solvents / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D014270:Trifluoroethanol / Q000494:pharmacology; D014364:Tryptophan / Q000737:chemistry*
D000939:Epitopes; D007074:Immunoglobulin G; D010455:Peptides; D012997:Solvents; D007073:Immunoglobulin E; D014270:Trifluoroethanol; D014364:Tryptophan