Eur. Phys. J. E 4, 115-120
Structure factor of a lamellar smectic phase with inclusions
P. Sens1 and M.S. Turner2.1 Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex, France
2 Rockefeller University, New York, NY 10021 USA and Department of Physics, Warwick University, Coventry, CV4 7AL, UK
sens@ics.u-strasbg.fr
(Received 10 March 2000 and Received in final form 30 August 2000)
Abstract
Motivated by numerous X-ray scattering studies of lamellar phases with
membrane proteins, amphiphilic peptides, polymers, or other
inclusions, we have determined the modifications of the classical
Caillé law for a smectic phase as a function of the nature and
concentration of inclusions added to it. Besides a fundamental
interest on the behavior of fluctuating systems with inclusions, a
precise characterization of the action of a given protein on a lipid
membrane (anchoring, swelling, stiffening ...) is of direct biological
interest and could be probed by way of X-ray measurements. As a first
step we consider three different couplings involving local pinching
(or swelling), stiffening or curvature of the membrane. In the first two
cases we predict that independent inclusions induce a simple
renormalization of the bending and compression moduli of the smectic
phase. The X-ray experiments may also be used to probe correlations
between inclusions. Finally we show that asymmetric coupling (such as
a local curvature of the membrane) results in a modification of the
usual Caillé law.
87.22.Bt - Membrane and subcellular physics and structure.
82.65.Dp - Thermodynamics of surfaces and interfaces.
82.70.-y - Disperse systems.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001