While performing biomolecular interaction analysis (BIA), scientists often
use surface plasmon resonance (SPR) to measure rate constants of the associ
ated reactions. A mathematical model of a BIAcore(TM), a common SPR device,
consists of a convection-diffusion equation in a channel with a reacting s
urface at the channel ceiling. Asymptotic and singular perturbation techniq
ues are used to analyse the concentration of the reacting species in two ca
ses: when the reaction occurs much more slowly than diffusion, and when the
reaction occurs on the same time-scale as diffusion. Linear and nonlinear
integral equations result from the analysis; explicit and asymptotic soluti
ons are constructed for physically realizable cases. These expressions prov
ide a direct way to estimate the rate constants from raw data.