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Optical Signal Transduction with an Emphasis on the Application of Surface Plasmon Resonance (SPR) in Antibody Characterisation
Published in Richard O’Kennedy, Caroline Murphy, Immunoassays, 2017
Caroline Murphy, Aoife Crawley, Hannah Byrne, Kara Moran, Jenny Fitzgerald, Richard O’Kennedy
The association kinetics of an interaction provides information on how fast an interaction occurs, i.e. how fast molecules A and B bind together. This is known as the association rate (ka). The dissociation rate (kd) gives information on how fast the molecules come apart and on how strong an interaction is. The association and dissociation rates are time-dependent and are written as follows:
Generalised expressions for the association and dissociation rate constants of molecules with multiple binding sites
Published in Molecular Physics, 2018
Adithya Vijaykumar, Pieter Rein ten Wolde, Peter G. Bolhuis
Arguably the most elementary event inside the living cell is a chemical reaction, be it a metabolic reaction, a chemical modification of a signalling protein, the binding of a gene regulatory protein to the DNA, or the hydrolysis of a fuel molecule that allows a motor protein to generate forces or move along a filament. Chemical reactions often involve the association and dissociation of two molecules. Some processes are controlled by the equilibrium constant of the association–dissociation reaction – the ratio of the association rate constant over the dissociation rate constant. For example, the average level of gene expression is, to a good approximation, determined by the binding probability of the gene regulatory protein to the promoter [1]. However, the living cell is a highly non-equilibrium system, and many, if not most, processes are governed by the absolute values of the rate constants. In protein signalling, the pathway for protein demodification is not the microscopic reverse of protein modification, setting up a cycle of modification and demodification. Not only the balance between modification and demodification, which sets the modification level (the output signal), but also the flux around the cycle, which determines the fuel consumption, is governed by the absolute rates of protein modification and demodification [2]. Many processes, such as cell division and cell differentiation during development, are directed by spatial protein patterns, and a key parameter in the formation of these patterns is the diffusion constant over the reaction rate. The slow binding of transcription factors to the DNA can be a major source of gene expression [3] and limit the speed of the response to a change in the environment [4]. Last but not least, recent studies indicate that the discrimination by the immune response does not rely on the binding probability of the antigen to the T-cell receptor, but rather on their dissociation rate [5].