title: Further studies on the specificity of the N- and C-terminal antigenic determinant of hen egg-white lysozyme.
abstract: The specificity of the N- and C-terminal antigenic determinant (P17: sequence Lys1-Cys6-Asn27, Trp123-Cys127-Leu129) of hen egg-white lysozyme (HL) was studied in more detail. In a Scatchard plot of the binding of 14C-acetyl HL with guinea pig purified anti-P17 antibody experimental values bent sharply near r=1. This suggests the presence of two antibody populations with different affinities for HL or possible steric hindrance in the binding of a second HL molecule to the second binding site of the antibody molecule. The antigenic activities of various peptides were tested by measuring their inhibition of the binding of 14C-acetyl-P17 with the anti-P17 antibody. Only P17 and P17t (sequence Lys1-Cys6-Homoser12, Trp123-Cys127-Leu129) were inhibitory, with KI values of 2.0 times 10(4) and 8.1 times 10(3), respectively. These results indicate that the direct binding site of P17 to anti-P17 antibody may be located in the terminal portion of P17 (sequence Lys1-Cys6-Homoser12, Trp123-Cys127-Leu129) while the rest of P17 may be important in maintaining the conformation of this determinant. The single disulphide blood involved in this determinant is essential for manifestation of immunological activity.
mesh_terms: D000818:Animals; D001666:Binding Sites, Antibody; D002645:Chickens; D004529:Egg White; D000939:Epitopes; D009113:Muramidase / Q000276:immunology*; D010443:Peptide Chain Termination, Translational; D010446:Peptide Fragments / Q000276:immunology*
chemical_list: D000939:Epitopes; D010446:Peptide Fragments; D009113:Muramidase