title: Effect of chemical modification and fragmentation on antigenic determinants of internal protein p30 and surface glycoprotein gp70 of type C retroviruses.
abstract: The effects of protein modification on the antigenic determinants of p30 and gp70 of type C retroviruses were investigated by using solid-phase competition radioimmunoassays. Proteins were modified by reduction with 2-mercaptoethanol and subsequent carboxymethylation of SH groups with iodoacetamide or by amidination of alpha and epsilon amino groups with methylacetimidate. The type-specific determinants of gp70 were found to be conformational in nature, as they were destroyed by these chemical modifications. Group- and interspecies-specific determinants of gp70 antigens, however, appear to be sequential and do not involve residues susceptible to these chemical reagents. Conformation-dependent type-specific determinants of p30 were affected only by methylacetimidate. Group- and interspecies-specific determinants of p30 are similar to those of gp70 in that they also appear to be sequential antigenic sites. Therefore, the broadly reactive group- and interspecies-specific determinants of gp70 and p30 can be followed into small peptides. Accordingly, a cyanogen bromide cleavage fragment derived from the carboxyl-terminal one-third of Rauscher leukemia virus p30 was found to carry group-specific determinants but no detectable interspecies-specific determinants. In contrast, a peptide obtained by limited trypsin cleavage of p30, which was derived from the NH(2)-terminal region of the protein, contained at least one of the interspecies determinants shared with feline leukemia virus p27.
mesh_terms: D000406:AKR murine leukemia virus / Q000276:immunology; D000956:Antigens, Viral / Q000032:analysis*; D000939:Epitopes; D006023:Glycoproteins / Q000276:immunology*; D007096:Imidoesters / Q000494:pharmacology; D007460:Iodoacetamide / Q000494:pharmacology; D005256:Leukemia Virus, Feline / Q000276:immunology*; D009052:Leukemia Virus, Murine / Q000276:immunology*; D008623:Mercaptoethanol / Q000494:pharmacology; D011487:Protein Conformation; D011925:Rauscher Virus / Q000276:immunology; D014764:Viral Proteins / Q000276:immunology*
chemical_list: D000956:Antigens, Viral; D000939:Epitopes; D006023:Glycoproteins; D007096:Imidoesters; D014764:Viral Proteins; D008623:Mercaptoethanol; C010222:methyl acetimidate; D007460:Iodoacetamide