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Antigen–Antibody Binding

  1. Izumi Kumagai1,
  2. Kouhei Tsumoto2

Published Online: 19 APR 2010

DOI: 10.1002/9780470015902.a0001117.pub2



How to Cite

Kumagai, I. and Tsumoto, K. 2010. Antigen–Antibody Binding. eLS. .

Author Information

  1. 1

    Tohoku University, Sendai, Japan

  2. 2

    The University of Tokyo, Tokyo, Japan

Publication History

  1. Published Online: 19 APR 2010


Antibodies are a family of glycoproteins that bind specifically to foreign molecules (antigens). The antibody-binding sites are formed by six segments of variable structure (CDRs) supported by a scaffolding of essentially invariant architecture (framework regions). Shape complementarity of binding surfaces (in the case of protein antigens) or close contact with small antigens (hapten, peptide or others), with some complementation of water molecules, is important. The binding of an antigen to an antibody takes place by the formation of multiple noncovalent bonds between the antigen and the amino acids of the binding site. The increase in van der Waals contancts and buried surfaces on complexation correlates well with the affinity, and hydrogen-bond formation is in principle critical for high specificity and affinity of an antibody for the target. Antibodies have at least two antigen-binding sites, which increase the apparent affinity, called avidity, of antibodies for the targets.

Key Concepts:

  • The binding between antibodies and antigens has high specificity and affinity resulting from various structural and energetic aspects. Multivalency of antibodies is important to understand the interaction of an antibody with its antigen.


  • antibody;
  • specificity;
  • affinity;
  • avidity;
  • complementarity-determining region