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Graduate Student :
Wesley D. Marner II |
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BS Chemical Engineering, Virginia Polytechnic Institute and
Co-Advised by Prof. Jay Keasling, group website
Office:
Phone: (510) 495-2625
Email: wmarner<<at>>uclink4.berkeley.edu
Nanostructured Biomaterials from Artificial Proteins and Biosilica
Nature is an expert at self-assembly and has the ability to create – on an extraordinary range of length scales – well-organized structures without external instruction. One example of this exceptional ability is the self-assembly of single-micron silk monomer proteins into strong fibers that are over two kilometers in length. Our aim is to harness some of these varied self-assembly mechanisms to design new materials suitable for a variety of applications. Specifically, we are investigating the usefulness of artificial protein polymers and biosilica matrices.
Protein polymers are found widely in nature in a variety of forms, and these materials exhibit a diverse array of physical properties. Through genetic engineering, artificially designed protein polymers can be designed with tailored mechanical properties as well as specific biochemical activity (enzymatic activities, cell signaling ability, etc.). One class of self-assembling proteins is hydrophobic-polar (HP) protein polymers. As a class, these proteins have an alternating hydrophobic/polar amino acid sequence, and they self-assemble via a stacked b-sheet mechanism into fibrous hydrogels under the appropriate solution conditions.
Using biosynthesis of these artificial proteins, from gene construction to purification of the expressed proteins from the bacterium Escherichia coli, we can produce high molecular weight protein polymers of precisely controlled amino acid sequence and molecular weight. Our labs have focused on a specific protein polymer, poly(EAK)n, and we are examining the morphology and physical properties of the hydrogels formed from this protein.
These studies also focus on the production of new biosilica matrices. Silica is one of the most abundant biominerals on Earth and is produced by a variety of organisms. One such organism is the diatom Cylindrotheca fusiformis. From dilute aqueous solutions of silica and using relatively mild processing conditions, these unicellular organisms create silica frustules with exquisite microstructures having feature sizes on the order of nanometers. C. fusiformis mediates the deposition of these silica features using a family of peptides called silaffins. Silaffin peptides are generally short (~15 amino acids) peptide sequences rich in lysine residues, and these peptides often have post-translational modifications that include polyamine chains and phosphate groups. In vitro, the silaffin R5 has been shown to direct the deposition of silica into spheres of defined sizes. We are currently exploring the self-assembly and silification capabilities of fusion proteins that combine a silaffin domain with a structural protein domain and describe the potential of these materials to produce silica matrices of designed microstructure.
Figure 1: SEM
micrograph of a hydrogel formed from a silaffin-poly(EAK)n
fusion protein.
Figure 2: SEM micrograph of a silca matrix
formed from a silaffin-poly(EAK)n fusion
protein.
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This page last updated 12/18/06 by Cari
http://www.cchem.berkeley.edu/~sjmgrp/people/wes/wes.htm