Antigen-Antibody Interactions: Strength or Antigen-Antibody Interactions.
The noncovalent interactions that form the basis of antigen-antibody(Ag-Ab)binding include hydrogen bonds,ionic bonds,hydrophobic interactions,and van der waals interactions.Because these interactions are individually weak(compared with a covalent bond),a large number of such interactions are required to form a strong Ag-Ab interactions.Furthermore,each of these noncovalent interactions operates over a very short distance,generally about 1 angstorms;consequently,a strong Ag-Ab interaction depends on a very close fit between the antigen and antibody.Such fits require a high degree of complementarity between antigen and antibody,a requirement that underlies the exquisite specificity that characterizes antigen-antibody interactions.
The noncovalent interactions that form the basis of antigen-antibody(Ag-Ab)binding include hydrogen bonds,ionic bonds,hydrophobic interactions,and van der waals interactions.Because these interactions are individually weak(compared with a covalent bond),a large number of such interactions are required to form a strong Ag-Ab interactions.Furthermore,each of these noncovalent interactions operates over a very short distance,generally about 1 angstorms;consequently,a strong Ag-Ab interaction depends on a very close fit between the antigen and antibody.Such fits require a high degree of complementarity between antigen and antibody,a requirement that underlies the exquisite specificity that characterizes antigen-antibody interactions.
Antibody Affinity Is a Quantitative Measure of Binding Strength.
The combined strength of a noncovalent interactions between a single antigen-binding site on an antibody and a single epitope is the affinity of the antibody for that epitope.Low-affinity of the antibodies bind antigen weakly and tend to dissociate readily,whereas high-affinity antibodies bind antigen more tightly and remain bound longer.The association between a binding site on an antibody(Ab)with a monovalent antigen(Ag)can be described by the equation.
Ag + Ab--------> Ag-Ab
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