title: Interfacial protein-protein associations.
abstract: While traditional models of protein adsorption focus primarily on direct protein-surface interactions, recent findings suggest that protein-protein interactions may play a central role. Using high-throughput intermolecular resonance energy transfer (RET) tracking, we directly observed dynamic, protein-protein associations of bovine serum albumin on polyethylene glycol modified surfaces. The associations were heterogeneous and reversible, and associating molecules resided on the surface for longer times. The appearance of three distinct RET states suggested a spatially heterogeneous surface - with areas of high protein density (i.e., strongly interacting clusters) coexisting with mobile monomers. Distinct association states exhibited characteristic behavior, i.e., partial-RET (monomer-monomer) associations were shorter-lived than complete-RET (protein-cluster) associations. While the fractional surface area covered by regions with high protein density (i.e., clusters) increased with increasing concentration, the distribution of contact times between monomers and clusters was independent of solution concentration, suggesting that associations were a local phenomenon, and independent of the global surface coverage.
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors.forename: Blake B
authors.initials: BB
authors.lastname: Langdon
authors.forename: Mark
authors.initials: M
authors.lastname: Kastantin
authors.forename: Robert
authors.initials: R
authors.lastname: Walder
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D002417:Cattle; D011092:Polyethylene Glycols / Q000737:chemistry / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs / Q000502:physiology*; D017434:Protein Structure, Tertiary; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols