Crystal structures of an antibody to a peptide and its complex with peptide antigen at 2.8 angstroms

Antibodies are molecules that preferentially bind (join) to antigens (foreign molecules), and understanding the antigen-antibody complex so formed can reveal much about the immune system's humoral division, which manufactures antibodies. Do antibodies associate with their antigens in a manner similar to a 'lock and key', or in a manner more like a handshake? Peptides are short segments of amino acids (the 'building blocks' of proteins) that can contain sequences identical to amino acid sequences that are part of large proteins. Such peptides, when injected into animals, can cause the production of antibodies that bind to both the peptide and the much larger protein, yet the mechanisms that allow this to happen are largely unknown. The immune system processes larger antigens into short peptides before they are presented to T cells (a white blood cell of the cellular immune system). Presentation is done by antigen-presenting cells (another type of blood cell), which have on their surface special proteins called MHC (major histocompatibility) proteins. It is possible that T cells recognize antigen in a manner similar to that of antibodies. A report of the structure of an antibody to one peptide, part of the structure of myohemerythrin, is provided. The technical details are discussed. With such structural data in hand, researchers are better equipped to understand how immune recognition occurs. (Consumer Summary produced by Reliance Medical Information, Inc.)