ma7b01742_si_001.pdf (152.3 kB)
Kinetics of Tethered Ligands Binding to a Surface Receptor
journal contribution
posted on 2017-10-18, 19:06 authored by Samuel Bell, Eugene M. TerentjevThe rate of binding of a grafted
polymer to the surface is controlled
by entropic barriers. Using a mean-field approximation of ideal polymer
dynamics, we first calculate the characteristic binding time for a
tethered ligand reaching for a binding site located on the tethering
surface. This time is determined by two separate entropic effects:
a barrier for the chain to be stretched sufficiently to reach the
distant target and a restriction on chain conformations near the surface,
versus the increase in available phase space for longer chains. The
competition between these two constraints determines the optimal (shortest)
binding time. The theory is then extended to model bridging between
two surfaces, in particular relevant for cell adhesion. Here the tethered
ligand reaches for a receptor on a parallel surface, and the binding
time depends on the gap between the two constraining surfaces. Again,
an optimal binding time is determined for the given tether geometry.
The results look similar to those for free particles in the “narrow
escape problem”, but modified by an entropic activation factor
introduced by the tether.