Does prediction of epitopes from the primary structure of a protein represent the epitope in the native structure? A study using cobrotoxin.
In contrast to observations made with S. aureus V8 protease-digest hydrolysates, the antigenic structures of reduced and S-carboxymethylated (RCM)-cobrotixin were notably affected following hydrolysis of RCM-cobrotoxin with chymotrypsin. The peptide separated from the V8 protease-digest hydrolysates with a sequence at positions 22-38 of cobrotoxin exhibited a nearly equal reactivity toward the anti-RCM-cobrotoxin antibodies as RCM-cobrotoxin. Chymotryptic cleavage on this segment caused a precipitous drop in the antigenicity of RCM-cobrotoxin. Alternatively, the N-terminal and C-terminal regions of RCM-cobrotoxin encompassed other antigenic determinants which exhibited low reactivities toward anti-RCM-cobrotoxin antibodies. The epitope structures of RCM-cobrotoxin are in line with those predicted from the hydrophobicity profile of cobrotoxin, but the notably immunoreactive region in the C-terminal region of native toxin molecule (Ref. 1) cannot be predicted from analysis of its primary structure. Moreover, RCM-cobrotoxin had a superior reactivity toward anti-RCM-cobrotoxin antibodies than cobrotoxin did. These results indicate that the epitope structures in RCM-cobrotoxin and cobrotoxin are different.
Chang
L S
LS
Department of Biochemistry, Kaohsiung Medical College, Kaohsiung, Taiwan, ROC.
Lin
S R
SR
Chang
C C
CC
D000906:Antibodies / Q000187:drug effects / Q000378:metabolism; D000941:Antigens / Q000302:isolation & purification / Q000494:pharmacology; D001666:Binding Sites, Antibody; D002918:Chymotrypsin; D003039:Cobra Neurotoxin Proteins / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D000939:Epitopes / Q000737:chemistry* / Q000276:immunology*; D006868:Hydrolysis; D008954:Models, Biological; D011487:Protein Conformation; D012697:Serine Endopeptidases; D013211:Staphylococcus aureus / Q000201:enzymology; D013329:Structure-Activity Relationship
D000906:Antibodies; D000941:Antigens; D003039:Cobra Neurotoxin Proteins; D000939:Epitopes; D012697:Serine Endopeptidases; D002918:Chymotrypsin; C028344:glutamyl endopeptidase