Difference Between Affinity and Avidity

Key Difference – Affinity vs Avidity

Antibody antigen interaction is a crucial interaction in cells to react against infections.Antigens是进入宿主细胞的异物。他们主要由多糖或者glycoproteinsand have particular shapes. The interaction between antigen and antibody occurs according to the correct binding of the two parties by the non-covalent bonds such as氢键,范德华的债券，等。这种交互是可逆的。亲和力和avidity are two parameters which measure the strength of the antigen-antibody interaction in immunology. The key difference between affinity and avidity is thataffinity is the measure of the strength of individual interaction between an epitope and one binding site of the antibody whereas avidity is the measure of the overall bindings between antigenic determinants and antigen binding sites of the multivalent antibody.亲和力is one factor which influences the avidity of the antigen antibody interaction.

内容
1.Overview and Key Difference
2.什么是亲和力
3.What is Avidity
4.Side by Side Comparison – Affinity vs Avidity
5.概括

什么是亲和力?

The affinity is a measure of the interaction between an antigen binding site of the antibody and an epitope of the antigen. Affinity value reflects the net result of the attractive and repulsive forces between individual epitope and individual binding site. High affinity value is a result of a strong interaction with more attractive forces between the epitope and Ab binding site. Low affinity value indicates the low balance between attractive and repulsive forces.

The affinity of monoclonal antibodies can be easily measured since they have a single epitope and are homogeneous. Polyclonal antibodies rate an average affinity value due to their heterogeneous nature and their differences in the affinities towards the different antigenic epitopes.

Enzyme-linked immunosorbent assay (Elisa) is a new technique in pharmacology which is used to measure the affinity of the antibodies. It results in more precise, convenient and informative data for affinity determination. High affinity antibodies bind with epitope quickly and make a strong bond which persists during the immunological assays while low affinity antibodies dissolve the interaction and are not detected by the assays.

What is Avidity?

The avidity of an antibody is a measure of the overall strength of the binding between the antigens and antibody. It depends on several factors such as affinity of the antibody towards the antigen, valence of antigen and antibody and the structural arrangement of the interaction. If the antibody and antigen are multivalent and have a favorable structural arrangement, the interaction remains very strong due to high avidity. Avidity always shows a high value than the summation of the individual affinities.

大多数抗原是多聚剂，大多数抗体都是多抗原。因此，由于抗原抗体复合物的高潮，大多数抗原抗体相互作用保持稳定和稳定。

亲和力和亲和力有什么区别？

亲和力vs Avidity
亲和力是指一个抗原表位与抗体的一个抗原结合位点之间相互作用的强度。	亲和力是抗原表位与多抗体之间相互作用的总体强度的度量。
发生
This occurs between individual epitope and individual binding site	这发生在多价抗原和抗体之间。
价值
亲和力is the balance of attractive and repulsive forces.	亲戚可以将其视为比单个亲和力的总和更多的价值。

概括– Affinity vs Avidity

Antigen antibody interaction is a specific, reversible, non-covalent interaction important in immunological studies. It is similar to the enzyme substrate interaction. Specific antigen binds with a specific antibody. Affinity and avidity are two measures of this interaction. Affinity reflects the strength of one interaction between an epitope and an antigen binding site of the antibody. Avidity reflects the overall strength of the antigen antibody complex. This is the difference between affinity and avidity. Avidity is a result of multiple affinities that occur in one antigen antibody complex since most antigens and antibodies are multivalent and maintain several interactions to stabilize the binding.

参考：
1. Rudnick，Stephen I.和Gregory P. Adams。“基于抗体的肿瘤靶向的亲和力和亲和力。”癌症生物疗法和放射药物。玛丽·安·利伯特（Mary Ann Liebert，Inc。），2009年4月。2017年3月21日
2. Sennhauser, F. H., R. A. Macdonald, D. M. Roberton, and C. S. Hosking. “Comparison of concentration and avidity of specific antibodies to E. coli in breast milk and serum.” Immunology. U.S. National Library of Medicine, Mar. 1989. Web. 22 Mar. 2017

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