Date of Award

2009

Degree Type

Thesis

Department

Chemical and Biomedical Engineering

First Advisor

Holland, Nolan

Subject Headings

Polypeptides, Elastin, Oligomerization domain, Foldon, ELP, GVGVP

Abstract

Elastin like polypeptides (ELPs) are an emerging class of biomaterials due to their unique group of chemical, physical and biological properties. We have constructed a library of ELPs based on the pentapeptide amino acid repeat sequence (GVGVP). ELPs exhibit lower critical solution temperature (LCST) transition behavior from a soluble phase below the transition temperature (Tt) to an insoluble two phase system above the transition temperature. This process is completely reversible so that ELPs can become soluble again upon lowering the temperature. This temperature can be tuned in many different ways at the molecular level by changing the composition of the amino acid sequence and by changing the molecular weight of the ELP. Solution parameters such as ELP concentration and NaCl concentration can also change the Tt of the ELP and these effects were investigated. An oligomerization domain, named foldon, was attached to the library of ELPs and termed (GVGVP)-foldon. The Tt's of GVGVP and (GVGVP)-foldon were measured using ultraviolet spectrophotometry over a range of ELP concentrations, lengths and solution properties. The oligomerization domain is expected to reduce the Tt of the ELPs in comparison to linear ELPs due to increased chain length, molecular weight, hydrophobic interactions and intrinsic concentration. The trimerizing behavior of the foldon motif was confirmed by SDS-PAGE gel analysis. The results showed that the addition of the foldon domain reduced the Tt of all ELP constructs over a range of chain lengths, ELP concentrations and solution parameters. However the effects of the foldon domain remain tied to the multi-variant effect that all ELPs show in regards to these factors. The ability to further alter the transitional properties of ELPs through the foldon domain increases our flexibility to make ELP constructs which are tunable to a wide range of desired transition temperatures

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