The position of the LysN epsilon H2-grafted antigens along the sequential oligopeptide carrier, Ac-(Aib-Lys-Aib-Gly)n (SOCn-II), influences the antibody recognition: application to the Sm main autoimmune epitope.
A sequential oligopeptide carrier of antigenic peptides is presented, incorporating two Aib residues in each repetitive moiety: Ac-(Aib-Lys-Aib-Gly)(n) (SOC(n) -II; n = 2-4). The conformational study, by (1)H-nmr, CD, and Fourier transform ir spectroscopy, indicated that the SOC(n) -II carrier displays a pronounced 3(10)-helix, compared to the Ac-(Lys-Aib-Gly)(n) (SOC(n) -I) carrier of the same approximately backbone length, previously reported. One of the dominant autoimmune epitopes of the Sm and U1RNP cellular components, the PPGMRPP sequence, was coupled to the Lys-N(epsilon)H(2) groups of the SOC(n) -II carrier and used as antigenic substrate for detecting anti-Sm/U1RNP autoantibodies in ELISA assays. Anti-Sm antibodies are highly specific for systemic lupus erythematosus, while anti-U1RNP are specific for mixed connective tissue disease. The anti-(PPGMRPP)(5)-SOC(n) -II ELISA was compared with the anti-(PPGMRPP)(n) -SOC(n) -I ELISA, provided that both antigenic substrates possess the same amount of the epitope replicates. The significance of the lysine positions along the oligopeptide backbone of the carrier for a favorable antibody recognition of the anchored antigens is also examined.
Alexopoulos
C
C
Department of Chemistry, University of Ioannina, P. O. Box 1186, 45110 Ioannina, Greece.
Tsikaris
V
V
Rizou
C
C
Sakarellos-Daitsiotis
M
M
Sakarellos
C
C
Cung
M T
MT
Marraud
M
M
Vlachoyiannopoulos
P G
PG
Moutsopoulos
H M
HM
D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000737:chemistry* / Q000276:immunology; D001323:Autoantibodies / Q000737:chemistry*; D001324:Autoantigens / Q000737:chemistry* / Q000276:immunology; D002352:Carrier Proteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000276:immunology; D002417:Cattle; D000939:Epitopes / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D008239:Lysine / Q000737:chemistry*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000276:immunology; D010446:Peptide Fragments / Q000737:chemistry* / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
D000941:Antigens; D001323:Autoantibodies; D001324:Autoantigens; D002352:Carrier Proteins; D000939:Epitopes; D009842:Oligopeptides; D010446:Peptide Fragments; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D008239:Lysine