BIOPHYSICAL THEORY AND MODELING |
A Coupled Diffusion-Kinetics Model for Analysis of Contact Area FRAP Experiment
Jianhua Wu 1, Ying Fang 1, Veronika I. Zarnitsyna 2, Timothy P. Tolentino 2, Michael L. Dustin 3 and Cheng Zhu 2*
1 South China University of Technology
2 Georgia Institute of Technology
3 New York University School of Medicine
* To whom correspondence should be addressed. E-mail: cheng.zhu{at}me.gatech.edu.
Submitted on June 5, 2007
Revised on July 31, 2007
Accepted on 18 March 2008
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Abstract |
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Kinetic rates and binding affinity of receptor-ligand interactions are important determinants of cell adhesion. Measurements of these parameters in fluid phase using soluble molecules (i.e., 3D parameters) do not necessarily correlate with their counterparts measured when both binding partners are respectively anchored to two apposing surfaces (i.e., 2D parameters). Moreover, 2D affinities measured by different methods can differ by orders of magnitude (Dustin et al., 2001, Annu. Rev. Cell Dev. Biol., 17: 133-157). Here we describe a coupled diffusion-reaction model for the fluorescence recovery after photobleaching (FRAP) experiment previously used to demonstrate the dynamics of adhesive bonds in the contact area (Dustin, J Biol Chem 272:15782-15788). Applying the mathematical model to the contact area FRAP experiment enables in situ measurements of 2D kinetic rates of the adhesion molecules and their retarded diffusion in a stable contact area. The mathematical properties of model are characterized in this paper and its experimental validation will be presented in the companion paper (Tolentino et al., 2008, Biophys. J. vol:pp-pp).
Key Words:
binding affinity, diffusion-reaction problem, rate constants
