In proteins, avidity is a term use to describe the combined strength of multiple bond interactions. Avidity is distinct from affinity, which is a term used to describe the strength of a single bond. As such, avidity is the combined synergistic strength of bond affinities rather than the sum of bonds.

It is commonly applied to antibody interaction, where multiple, weak, non-covalent bonds form between antigen and antibody. Individually, each bond is quite readily broken, however when many are present at the same time the overall effect results in synergistic, strong binding of antigen to antibody (ex: IgM is said to have low affinity but high avidity because it has 10 weak binding sites as opposed to the 2 strong binding sites of IgG, IgE, and IgD).

If the clustered proteins form a matrix, such as a clathrin-coat, the interaction is described by the term matricity.

ee also

*Amino acid residue
*Fab region

External links



*Roitt, Ivan, "et al.", "Immunology", 6th edn, 2001, Mosby Publishers, page 72.

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  • Avidity — A*vid i*ty, n. [L. aviditas, fr. avidus: cf. F. avidit[ e]. See {Avid}.] Greediness; strong appetite; eagerness; intenseness of desire; as, to eat with avidity. [1913 Webster] His books were received and read with avidity. Milward. [1913 Webster] …   The Collaborative International Dictionary of English

  • avidity — (n.) mid 15c., eagerness, zeal, from O.Fr. avidite avidity, greed, from L. aviditatem (nom. aviditas) eagerness, avidity, noun of quality from avidus (see AVID (Cf. avid)) …   Etymology dictionary

  • avidity — index desire, greed, passion Burton s Legal Thesaurus. William C. Burton. 2006 …   Law dictionary

  • avidity — noun a) Greediness; strong appetite. to eat with avidity b) Eagerness; intenseness of desire Come, walk up, and purchase with avidity,Overcome your diffidence and natural timidity. Syn: eagerness …   Wiktionary

  • avidity — The binding strength of an antibody for an antigen. [L. avidus, greedy, eager fr. aveo, to crave] * * * avid·i·ty (ə vidґĭ te) 1. the strength of an acid or a base. 2. the strength of binding between antibody and a complex antigen.… …   Medical dictionary

  • avidity — avid ► ADJECTIVE ▪ keenly interested or enthusiastic. DERIVATIVES avidity noun avidly adverb. ORIGIN Latin avidus, from avere crave …   English terms dictionary

  • avidity — noun (plural ities) Date: 15th century 1. the quality or state of being avid: a. keen eagerness b. consuming greed 2. affinity 2b(2) …   New Collegiate Dictionary

  • avidity — the frequency of fishing activity, e.g. the number of days on which fishing trips were made …   Dictionary of ichthyology

  • avidity — Strength of binding, usually of a small molecule with multiple binding sites by a larger; particularly the binding of a complex antigen by an antibody. (Affinityrefers to simple receptor ligand systems.) …   Dictionary of molecular biology

  • avidity — /euh vid i tee/, n. 1. eagerness; greediness. 2. enthusiasm or dedication. [1400 50; late ME avidite < MF < L aviditas. See AVID, ITY] * * * …   Universalium