Steric hindrance effects in thin reaction zones: applications to BIAcore

Abstract

Many biological and industrial processes have reactions which occur in thin zones of densely packed receptors. Understanding the rate of such reactions is important, and the BIAcore surface plasmon resonance biosensor for measuring rate constants has such a geometry. However, interpreting biosensor data correctly is difficult since large ligand molecules can block multiple receptor sites, thus skewing the kinetics. General mathematical principles are presented for handling this phenomenon, and a receptor layer model is presented explicitly. An integro-partial differential equation results. Using perturbation techniques, the problem can be simplified somewhat. In the limit of small Damköhler number, the non-local nature of the system becomes evident in the association problem, while other experiments can be modelled using local techniques. Explicit and asymptotic solutions are constructed for large-molecule cases motivated by experimental design. The analysis provides insight into surface-volume reactions occurring in various contexts. In particular, this steric hindrance effect can often be quantified with a single dimensionless parameter.

Ultra sensitive affinity chromatography on avidin-functionalized PMMA microchip for low abundant post-translational modified protein enrichment

“…This is due to the fact that the reaction rate becomes infinitely fast, so the system becomes transport limited. On the other hand, if k a is too small, there has not been enough binding for occlusion effects to play a role (Edwards 2007). Based on Edwards' study, for our application of biotin-avidin binding with a relatively high association rate of 7×10 7 M −1 s −1 (Piran et al 1990), the steric hindrance is referred as 0.0005 s −1 .…”

Biomolecular Detection Based on the Rotational Dynamics of Magneto-Plasmonic Nanoparticles

“…However, they still face intrinsic problems such as steric hindrance [1], restricted diffusion [2] and extensive sample preparations that limit their applicability at point-of-care [3]. These issues can be circumvented in homogeneous immunoassay principles, where the signal generating probes are mixed with the analyte sample followed by a target molecule detection directly within the probe-analyte mixture.…”