Biomolecular Materials

S-layer Protein Bioconjugates

The self-assembling proteins that form crystalline surface layers (S-layers) on many microbial species have found numerous applications due to their nanostructured nature. In order to devise a new method to construct surface displays that exploit their self-assembly activity and nanostructural properties we have constructed polymer bioconjugates of S-layer proteins from Lactobacillus brevis. The conjugates formed are similar in function to the monomer alkanethiols that form self-assembled monolayers (SAMs) on gold surfaces. However, the self-assembly is driven by the protein “headgroup” that positions polymer tethered endgroups on a surface. The surfaces obtained exhibited homogeneous distributions of tethered molecules, and in cases where the modular assembly of two distinct types of tethered endgroups was accomplished there was no evidence for phase separation in the surfaces. The modular assembly method will provide a potential route to controlling surface display density as starting assembly conditions guide surface formation in mixed monolayer formation.

Sampathkumar, P. and Gilchrist, M. L., (2004) Synthesis and Characterization of Bioconjugates of S-layer Proteins Bioconjugate Chemistry 15(4) 685-693.

Bacteriorhodopsin Conjugates as Anchors for Supported Membranes

The sophistication of supported lipid bilayer membranes has increased steadily as new applications are being explored. In general, tethered lipids are used to anchor the lipid bilayer to the substrate. Here we describe a new type of anchoring system for supported lipid bilayers that is based on biotin-PEG3400-bacteriorhodopsin conjugates. Amine-based coupling was used to construct the polymer conjugates, followed by fluorophore labeling to enable confocal imaging. The bacteriorhodopsin-based anchoring system was used to construct solid-supported vesicles from streptavidin-coated microspheres. This method could provide a new route for the stability enhancement of supported lipid bilayer membrane assemblies.

Sharma, M.K. Jattani, H. and Gilchrist, M. L., (2004) Bacteriorhodopsin Conjugates as Anchors for Supported Lipid Bilayers Bioconjugate Chemistry 15(4) 942-947.