TY  - GEN
A1  - Walkowiak, Jacek
A1  - Lu, Yan
A1  - Gradzielski, Michael
A1  - Zauscher, Stefan
A1  - Ballauff, Matthias
T1  - Thermodynamic analysis of the uptake of a protein in a spherical polyelectrolyte brush
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - A thermodynamic study of the adsorption of Human Serum Albumin (HSA) onto spherical polyelectrolyte brushes (SPBs) by isothermal titration calorimetry (ITC) is presented. The SPBs are composed of a solid polystyrene core bearing long chains of poly(acrylic acid). ITC measurements done at different temperatures and ionic strengths lead to a full set of thermodynamicbinding constants together with the enthalpies and entropies of binding. The adsorption of HSA onto SPBs is described with a two-step model. The free energy of binding Delta Gb depends only weakly on temperature because of a marked compensation of enthalpy by entropy. Studies of the adsorbed HSA by Fourier transform infrared spectroscopy (FT-IR) demonstrate no significant disturbance in the secondary structure of the protein. The quantitative analysis demonstrates that counterion release is the major driving force for adsorption in a process where proteins become multivalent counterions of the polyelectrolyte chains upon adsorption. A comparison with the analysis of other sets of data related to the binding of HSA to polyelectrolytes demonstrates that the cancellation of enthalpy and entropy is a general phenomenon that always accompanies the binding of proteins to polyelectrolytes dominated by counterion release.
KW  - ITC
KW  - spherical polyelectrolyte brushes
KW  - enthalpy-entropy compensation (EEC)
KW  - proteins
KW  - thermodynamics
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-517307
SN  - 1866-8372
IS  - 1
ER  - 
TY  - JOUR
A1  - Schmidt, Joachim
T1  - Die Arbeit bei irreversibler Druck-Volumen-Änderung
BT  - Varianten der Berechnung
N2  - For the calculation of the work in an irreversible pressure-volume change, we propose approxima-tions, which in contrast to the usual representation in the literature reflect the work performed during expansion and compression symmetrically. The calculations are based on the Reversible-Share-Theorem: Is used the force to overcome for calculating the work, so it captures only the configurational reversible work share.
KW  - physics
KW  - physical chemistry
KW  - thermodynamics
KW  - irreversible volume-change
KW  - reversible-share-theorem
KW  - total work
KW  - reversible work share
KW  - irreversible work share
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-74931
ER  -