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Protein Adsorption at Air-Water Interfaces: A Combination of Details

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Author: Jongh, H.H.J.de · Kosters, H.A. · Kudryashova, E. · Meinders, M.B.J. · Trofimova, D. · Wierenga, P.A.
Type:article
Date:2004
Institution: TNO Voeding
Source:Biopolymers, 1-2, 74, 131-135
Identifier: 237740
doi: doi:10.1002/bip.20036
Keywords: Nutrition · Food technology · Adsorption · Air-water interfaces · Circular dichroism · Drop tensiometry · Ellipsometry · External reflection · Fluorescence · Infrared · Adsorption · Electrostatics · Ellipsometry · Hydrophobicity · Molecular dynamics · Chemical reactivity · Electrostatic repulsion · Surface pressure · Tensiometry · Proteins · carboxylic acid · functional group · protein · solvent · water · adsorption · air water interface · analytic method · circular dichroism · concentration (parameters) · conference paper · drop tensiometry · electricity · ellipsometry · external reflection · fluorescence spectroscopy · hydrophobicity · infrared spectroscopy · measurement · molecular dynamics · oscillation · pressure · protein aggregation · protein folding · protein interaction · proton transport · solvation · spectroscopy · surface property · thickness · Adsorption · Air · Animals · Biophysics · Carboxylic Acids · Cattle · Chickens · Circular Dichroism · Electrostatics · Hydrogen-Ion Concentration · Kinetics · Pressure · Proteins · Spectrometry, Fluorescence · Spectrophotometry, Infrared · Surface Properties · Time Factors · Water

Abstract

Using a variety of spectroscopic techniques, a number of molecular functionalities have been studied in relation to the adsorption process of proteins to air-water interfaces. While ellipsometry and drop tensiometry are used to derive information on adsorbed amount and exerted surface pressure, external reflection circular dichroism, infrared, and fluorescence spectroscopy provide, next to insight in layer thickness and surface layer concentration, molecular details like structural (un)folding, local mobility, and degree of protonation of carboxylates. It is shown that the exposed hydrophobicity of the protein or chemical reactivity of solvent-exposed groups may accelerate adsorption, while increased electrostatic repulsion slows down the process. Also aggregate formation enhances the fast development of a surface pressure. A more bulky appearance of proteins lowers the collision intensity in the surface layer, and thereby the surface pressure, while it is shown to be difficult to affect protein interactions within the surface layer on basis of electrostatic interactions. This work illustrates that the adsorption properties of a protein are a combination of molecular details, rather than determined by a single one. © 2004 Wiley Periodicals, Inc.