A kinetic model of partially reversible protein adsorption

Abstract

Determination of fluid-solid transitions in model protein solutions using the histogram reweighting method and expanded ensemble simulations Monte Carlo studies of the thermodynamics and kinetics of reduced protein models: Application to small helical, β, and α/β proteins We present a kinetic adsorption model for proteins that accounts for the experimentally observed properties of partial reversibility and surface induced conformational change. Particles ͑proteins͒ are modeled as disks that adsorb sequentially and without overlap at random positions onto a surface. Following adsorption, a particle can either desorb or spread symmetrically to a larger size. If the latter occurs, it remains adsorbed irreversibly. Both of these events obey first order kinetic rate laws. We derive analytical results in the asymptotic regime and report Monte Carlo results for shorter times. This model yields adsorbed phases that are more dense than those predicted by models of purely irreversible adsorption. We attribute this densification to a fluid structure that is quite liquidlike. We show that a number of experimentally observed kinetic behaviors can be reproduced with this model and that it is in good quantitative agreement with recent experiments.

Conformation and orientation of a protein folding intermediate trapped by adsorption

“…This structural heterogeneity is explained by the altered conditions experienced by proteins that arrive late at the interface during the adsorption process (18)(19)(20)(21). Protein molecules that arrive first at the interface have sufficient space to adapt to the interface, allowing conformational changes like expansion to a molten globule to occur.…”

History dependence of protein adsorption kinetics

“…To see why this is so, we consider the picture of partially reversible protein adsorption in which molecules initially attach in a reversible manner (with a structure similar to that in solution) and subsequently undergo an irreversible transition to a conformationally or orientationally altered structure possessing a greater degree of surface contact (16,35). Within this picture, steric blocking of the transition prevents some of the molecules from becoming irreversibly bound; this explains observations of (i) a removal of only a certain fraction of adsorbed proteins during dilution of the bulk phase and (ii) an increase in maximal surface coverage with protein bulk concentration (36,37).…”

“…For example, kinetic models accounting for history dependence through an irreversible change in internal protein conformation (16)(17)(18), although accurate to intermediate times, begin to deviate from experiment somewhat at longer times (19). Multistep adsorption analysis can serve as a systematic test of model assumptions and provide clues as to whether effects other than internal protein rearrangements might contribute to history dependence in a significant way.…”

Investigation of Ferritin Desorption from Gold Initiated by In Situ pH-Change

“…Protein adsorption on surfaces is a well-studied phenomenon, as protein-surface interactions are present in life and are useful for technological applications [1][2][3][4][5][6][7]. At the same time they are sometimes undesirable, as they can lead to formation of biofilms or cause thrombosis [5].…”

“…Various theories were developed to analyse these processes and there are several experimental reports [6][7][8][9]. However, there exists no entirely satisfactory, comprehensive theory.…”