IMMUNOCHEMICAL STUDIES ON TOBACCO MOSAIC VIRUSPROTEIN .9. INVESTIGATIONS ON BINDING AND ANTIGENIC SPECIFICITY OF ANTIBODIES TO AN ANTIGENIC AREA OF TOBACCO MOSAIC VIRUS PROTEIN

Previous reports from this laboratory showed that antibodies produced by all rabbits in response to immunization with tobacco mosaic virus protein bind with a decapeptide representing residues 103-112 of the protein and having the sequence Thr-Thr-Ala-Glu-Thr-Leu-Asp-Ala-Thr-Arg. It was further shown that whereas no binding could be demonstrated between antibodies and the C-terminal di-, tri-, or tetrapeptide, antibodies produced by some rabbits bind with the C-terminal pentapeptide while those produced by other rabbits require the C-terminal hexa- or heptapeptide portions of the decapeptide for demonstrable binding. A subsequent report from this laboratory showed that N octanoylation of the C-terminal tetrapeptide conferred activity upon the peptide. Using V-octanoylpeptides the present work demonstrates that antibodies produced by all the rabbits tested bind with the octanoylated C-terminal tripeptide portion of the decapeptide, namely with octanoyl-Ala-Thr-Arg. It is postulated that the differences which exist between antibodies produced by different rabbits with respect to reactivity with peptides consisting of C-terminal portions of the decapeptide are due to differences in the binding affinities with these peptides. In addition, experiments with closely related octanoylated analogs of the above tripeptide indicated differences between antibodies produced by different animals which are probably due to differences in antibody specificity. © 1969, American Chemical Society. All rights reserved.