Antigenic determinants lysozyme

It appears to be generally accepted that, at least for lysozyme, most of the antigenic determinants are assembled topographic determinants. This concept is supported by the observation that little or no crossreactivity occurs between native and denatured lysozymes (Thompson etal., 1972). 

The antigenic determinants of the native lysozyme molecule appear to include most, if not all, of the surface residues, as evidenced by numerous studies (reviewed critically by Benjamin et al., 1984). This point of view contrasts with that of Atassi and Lee (1978), who claimed a limited antigenicity, based on a study of surface-simulated peptides. The sites delineated by the latter workers do not include Arg-68 (Fainanu et al., 1974), the loop region in general, or any of several other segmental regions previously demonstrated to function in this capacity, such as residues 1—20 and 123-129 (see Benjamin et al., 1984). 

The occurrence of cross-reactions with lysozymes of various species may contribute substantially to the precise delineation of the antigenic determinants. Turkey and bobwhite quail lysozymes differ from that of chicken in that Arg replaces Lys at positions 73 and 68, respectively. Turkey lysozyme reacted identically but quail lysozyme was weaker, thus indicating that Arg-68 makes a greater contribution to the interaction with the antibody combining site. 

S.Shinka, M.Imanishi, N.Miyagawa, T. Amano, M.Inouve and A.Tsugita, Chemical Studies on Antigen Determinants of Hen Eggwhite Lysozyme, Biken s J. 10, 89-107 (1967). 

Purified antibody populations directed toward distinct antigenic determinants were also obtained for various other proteins [e.g., sperm whale myoglobin (Atassi, 1975) and lysozyme (Atassi and Lee, 1978a,b)] (see Section 9.1.2). 

The study by Determan et al. [224] focuses on the effects of polymer degradation products on the primary, secondary, and tertiary structure of TT, OVA, and lysozyme after incubation for 0 or 20 days in the presence of ester (lactic acid and glycolic acid) and anhydride [sebacic acid and l,6-bis(p-carboxyphenoxy)hexane] monomers. The structure and antigenicity or enzymatic activity of each protein in the presence of each monomer was quantified. SDS-PAGE, circular dichroism, and fluorescence spectroscopy were used to assess/evaluate the primary, secondary, and tertiary structures of the proteins, respectively. ELISA was used to measure changes in the antigenicity of TT and OVA and a fluorescence-based assay was used to determine the enzymatic activity of lysozyme. TT toxoid was found to be the most stable in the presence of anhydride monomers, while OVA was most stable in the... 

The lysozyme molecule was determined to have three antigenic sites with residues coming from widely separated portions of the polypeptide chain the residues proposed as contacting and those synthesized to produce a linear sequence considered as best simulating the active site are seen in Fig. 15. In some instances the peptide synthesized in the reverse direction —for example, using the C-terminal amino acid of the hypothesized determinant as the amino terminus—was used as a control. In some instances, the sequence was considered to have directionality whereas in others it did not. 

When an acridonylalanine (acdAla) was incorporated at different positions of camel single-chain antibody against hen-lysozyme, the Tyrl06acdAla mutant sensitively responded to the binding of nanomolar concentration of the antigen, whereas the Trpl23acdAla mutant was insensitive to the binding (Fig. 5.1-16) [71]. When the same fluorescent amino acid was incorporated into streptavidin, some mutants responded to even a picomolar quantity of biotin [71]. The lower limit of the detectable concentration is determined not by the fluorescence sensitivity, but by the dissociation constants of the protein-small molecule interactions. 

The three-dimensional structures of approximately 30 complexes between antibodies and various protein antigens have been determined in recent years, including hen egg white lysozyme (HEL) (Amit et al., 1986 Sheriff ct a/., 1987 Padlaneta/., 1989 Chitarra et a/., 1993 Braden eta/., 1994 Rondo et al., 1999 Li et al., 2000), influenza virus neuraminidase (Colman et al., 1987 Tuhp et al., 1992 Malby et al., 1994), horse cytochrome c (Mylvaganam et al., 1998), human tissue factor (Huang et al.,... 

The exact boundary, residue, conformational, and directional definitions of the three antigenic sites of hen egg-white lysozyme have been described. The results revealed that the three antigenic sites account quantitatively for the total antigenic reactivity of the protein. Thus the entire antigenic structure of the enzyme has now been determined precisely. Its nature was discussed together with the power of the surface-simulation synthetic concept. 

Several surface-simulation synthetic peptides have been synthesized in order to investigate the conformation restrictions of the antigenic site of hen egg-white lysozyme and to determine if the spatially constructed antigenic site has a preferred direction . The results from interaction direct and via immuno-adsorption showed that the peptide (IS) possessed the maximum inhibitory... 

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