Biological Membranes

Penghui LinNov. 15. 2013

Membranes

http://www.uvm.edu/~inquiryb/webquest/fa06/mvogenbe/

Diffusion across plasma membrane

http://en.wikipedia.org/wiki/Cell_membrane

Plasma Membrane

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Man-made membrane

http://bioweb.wku.edu/courses/biol115/wyatt/biochem/lipid/Lipid_2.asp

Liquid crystals

• Nematic phase

• Smectic phases

• Chiral phases

http://en.wikipedia.org/wiki/Liquid_crystal

Sample preparation

Jörg Fitter, Thomas Gutberlet, John Katsaras. Neutron Scattering in Biology, Techniques and Applications. 2006 ISBN: 978-3-540-29108-4 (Print) 978-3-540-29111-4 (Online)

Incident angle = reflected angle

Specular Neutron Reflectivity

Jörg Fitter, Thomas Gutberlet, John Katsaras. Neutron Scattering in Biology, Techniques and Applications. 2006 ISBN: 978-3-540-29108-4 (Print) 978-3-540-29111-4 (Online)

Density profile ρ0(z)

Fourier Synthesis

Jörg Fitter, Thomas Gutberlet, John Katsaras. Neutron Scattering in Biology, Techniques and Applications. 2006 ISBN: 978-3-540-29108-4 (Print) 978-3-540-29111-4 (Online)

Lipid bilayer phases

Location of Cholesterol

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Location of cholesterol

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Forces between membranes

Disjoining pressureOsmotic pressure

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Osmotic stress experiment

Neutron/

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Thermal unbinding

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Single component membrane

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Lipid mixtures and domains

• Ideal mixing: no phase separation

• Non-ideal or non-random mixing: compositional fluctuation happens while no stable domains formed

• Macroscopic phase separation: micron-size stable lipid domains are formed

No phase separation

Membranethickness

Fluctuationparameter

in DMPC bilayers at 35°Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Macroscopic phase separationDPPC/DOPC/cholesterol

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Supramolecular properties

Diffused scattering

Tilted phase

Interdigitated phase

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Bicelle mixtures

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Bicelle mixtures

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Fluctuation change upon antimicrobial peptide binding

Jörg Fitter, Thomas Gutberlet, John Katsaras. Neutron Scattering in Biology, Techniques and Applications. 2006 ISBN: 978-3-540-29108-4 (Print) 978-3-540-29111-4 (Online)

Membrane rigidity change

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Pabst G. Applications of neutron and X-ray scattering to the study of biologically relevant model membranes J.Chem Phys Lipids. 2010 Jun;163(6):460-79

Thanks!

Jörg Fitter, Thomas Gutberlet, John Katsaras. Neutron Scattering in Biology, Techniques and Applications. 2006 ISBN: 978-3-540-29108-4 (Print) 978-3-540-29111-4 (Online)