JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 85 No. 11 2711-2721
© 2002 by American Dairy Science Association ®
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Marchesseau, S.
Right arrow Articles by Pugnière, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Marchesseau, S.
Right arrow Articles by Pugnière, M.

Casein Interactions Studied by the Surface Plasmon Resonance Technique

S. Marchesseau*, J-C. Mani{ddagger}, P. Martineau{dagger}, F. Roquet{dagger}, J-L. Cuq* and M. Pugnière{dagger}

* Laboratoire de Génie Biologique et Sciences des Aliments, Université Montpellier II, 34095 Montpellier Cedex 5, France
{dagger} CNRS UMR 5094, Institut de Biotechnologie et Pharmacologie, Faculté de Pharmacie, 34093 Montpellier Cedex 5, France
{ddagger} The paper is dedicated to the memory of Dr. Jean-Claude Mani

Corresponding author:
M. Pugnière; e-mail:
martine.pugniere{at}ibph.pharma.univ-montp.fr.

Surface plasmon resonance technique was investigated for the first time to study the apparent hydrophobicity and association properties of the major bovine caseins: {alpha}s-({alpha}s1- and {alpha}s2-caseins in a 4:1 proportion),ß-, and {kappa}-caseins. The apparent hydrophobicities of the caseins were evaluated by a new method based on the binding level of casein on a hydrophobic sensor chip, and kinetic and equilibrium affinity constants were determined for the following casein interactions: {alpha}s/{alpha}s, {alpha}s/ß, {alpha}s/{kappa}, ß/ß, and ß/{kappa}, using a sensor chip modified with covalent immobilized caseins. The study by surface plasmon resonance technology of these casein interactions under different conditions (pH, ionic strength, calcium concentration, chemical modification) demonstrated that, at neutral pH, electrostatic repulsive forces play an important role since an increase in ionic strength of the medium resulted in a stronger interaction. When charge repulsions were reduced by either acidification, increase in ionic strength, or dephosphorylation, casein interactions were reinforced, presumably due to weak attractive forces. Moreover, in this molecular model, we showed that addition of calcium greatly increased the binding response between the most phosphorylated caseins and that the added calcium (2 mM) participated directly in the formation of bridges between the phosphate groups of the casein molecules.

Key Words: bovine casein • casein interaction • surface plasmon resonance • BIACORE

Abbreviation key: ka = association rate constant, kd = dissociation rate constant, KD = equilibrium dissociation constant, P20 = polyoxyethylenesorbitan, Ru = resonance unit, SPR = surface plasmon resonance






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2002 by the American Dairy Science Association ®.