CHAPTER II
METHODS FOR THE DETERMINATION OF ASSOCIATION AND
DISSOCIATION RATE CONSTANTS AND FOR THE ESTIMATION OF TIMES
REQUIRED FOR THE ATTAINMENT OF ARBITRARY DEGREES OF APPROACH
TO EQUILIBRIUM BY NON-COOPERATIVE, SINGLE SITE
LIGAND-RECEPTOR SYSTEMS
Introduction
The rate equation for noncooperative, single site ligand binding
systems may be written
dBL/dt = ka (SL-BL)(B0-BL)-kdBL, (2-1)
where B^ is the concentration of specifically-bound ligand, S^ is the
total ligand concentration, Bq is the total concentration of binding
sites, ka and k^ are the second-order and first-order association and
dissociation rate constants, and t is the time of incubation. The exact
solution to this equation gives the value of B^ as a function of time
for the given incubation conditions if the rate constants (or the
equilibrium dissociation constant, K^, and one of the rate constants)
and the concentration of ligand and binding sites are known (e.g., De
Lean and Rodbard, 1979; Vassent, 1974). Thus, if nonspecific binding
and loss due to the inactivation of binding sites may be neglected as an
approximation, the solution to the rate equation provides an estimate of
the time required for any arbitrary degree of approach to the
equilibrium value of specific binding. As an example of its utility,
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