Susan Daniel, a Post-doc in the Department of Chemistry at Texas A & M University, presents Protein Mobility, Filtering, and Separation in Model Cell Membranes as part of ChBE's spring seminar series.

* Refreshments will be served at 3:30 PM in the Lower Level 1 Gossage Atrium
* Lecture commences at 4:00 PM in L1255 in the Ford ES&T Building

Seminar Abstract
Investigating how biomolecules behave in cell membranes gives us insight that can be used to
create better assays, sensors, and devices that mimic the cell surface. Applications for these
devices include rapid combinatorial analysis of drug targets, biosensors for toxin detection, and
proteomics research. Solid-supported lipid bilayers (SLBs) are an excellent platform for
mimicking the surface chemistry of cells. However, there are several drawbacks to these
platforms. First, proteins can lose their mobility in these systems, impairing their function.
Second, there is no good way to discriminate between analytes that bind to the same surface
ligand within these platforms. Third, separation, purification, and formation of arrays of
membrane species is difficult, impeding the progress of rapid combinatorial assaying of
membrane proteins.

Results will be presented on studies conducted to understand these issues and strategies to
overcome them. By investigating the behavior of protein-protein interactions on SLBs, we found
that protein-packing influences the point at which diffusion is arrested in these systems. To
improve binding specificity, we devised a system for size-selective discrimination of protein
analytes that bind to the same ligand, by incorporating poly(ethylene glycol) (PEG) lipopolymers
into SLBs. Using our platform, we were able to achieve discrimination of several orders of
magnitude. Finally, we developed a technique to separate membrane species within an SLB:
bilayer chromatography. Results will be presented that show our separation method is sensitive
enough to differentiate isomers of dye-labeled lipids and is currently being extended to the
separation of membrane proteins.