BIO 447 Lecture Notes - Lecture 4: Mhc Class I, Mhc Class Ii, Toxicodendron Radicans
Document Summary
Antibody-epitope = weak non-covalent bonds (operate over short distances) Strong bond by complementary shaping (amino acids, chemical environment) Composed of accessible, hydrophilic amino acids on protein surface. X-ray crystallographic analyses show that antibodies make contact with antigens on flat surfaces where the depressions/protrusions match. Either sequential, continuous residues on polypeptide chain or non- sequential residues from segments brought together by folding. Non-sequential epitopes conformational = far apart on primary aa sequence, but close on tertiary structure. Major antigenic determinants are usually located in the most mobile regions. Some epitopes are immunodominant = induce more pronounced immune response than other epitopes. Do not recognize native antigens, but processed antigenic peptides. Before t-cell can be activated, must have a tri-molecular complex of antigen-binding receptor, mhc molecule, and antigenic peptide: must have 2 interaction sites, epitope interacts with t-cell receptor, agretope interacts with mhc. Nonamers = 9 amino acids, bind most strongly.
