Molecular recognition in antibody-antigen complexes.
With the numerous detailed molecular descriptions of antibody-antigen interfaces, the structual study of these molecular interactions has evolved from an attempt to understand to immunological function to their use as model systems for protein-protein interactions. In this chapter, we describe the structual aspects common to antibody-antigen interfaces  and discuss the roles they may play in antibody cross-rectivity and molecular mimicry. More detailed analysis of these interfaces has required the marriage of structural studies with extensive mutagenesis and thermodynamic analysis efforts. Here, we discuss the thermodynamic mapping of interfaces for two model antibody-antigen complexes, including the identification of thermodynamic hot spots in binding and the various mechanism used to accommodate interface mutations. We also discuss the functional roles for protein plasticity in antigen recognition, including the entropic control of antibody affinity maturation and the use of induced  fit mechanism of different types and to varying degrees by mature antibodies in binding their specific antigens.
Sundberg
Eric J
EJ
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA.
Mariuzza
Roy A
RA
D000818:Animals; D000936:Antigen-Antibody Complex / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D001666:Binding Sites, Antibody; D003429:Cross Reactions; D006801:Humans; D018448:Models, Immunological; D008958:Models, Molecular; D018716:Molecular Mimicry; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry / Q000276:immunology; D013816:Thermodynamics
D000936:Antigen-Antibody Complex; D011506:Proteins