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J Immunol Methods. 2003 May 1;276(1-2):129-34.

Unexpected observation of concentration-dependent dissociation rates for antibody-antigen complexes and other macromolecular complexes in competition experiments.

Author information

1
Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETHZ, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.

Abstract

The dissociation rate constant of bimolecular complexes between macromolecules (k(off)) is often measured in solution by competition experiments and is generally expected to follow first-order kinetics.When measuring k(off) constants by competition for three complexes of high-affinity recombinant antibody fragments with the cognate antigen and for one calmodulin/peptide complex, a surprising dependence between apparent dissociation rate and concentration of competitor (antigen or calmodulin-binding peptide) was observed. Our results may be characteristic for macromolecules consisting of two domains (such as single-chain Fv fragments) and may reflect a transient opening of the two domains which are involved in the binding reaction, and which are connected by a polypeptide linker.

PMID:
12738365
DOI:
10.1016/s0022-1759(03)00060-7
[Indexed for MEDLINE]

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