Presentation Abstract

Session Title: Platform: Protein Assemblies, Aggregates, & Chaperones
Location: Room 113C
Presentation Number: 2838-Plat
Presentation Time: 2/6/2013 1:00:00 PM
Abstract Title: BIOPHYSICAL ANALYSIS OF A NOVEL DRUG DELIVERY VECTOR: ELP[V5G3A2-150]
Author Block: Daniel Lyons1, Vu Le2, Gene L. Bidwell1, Wolfgang Kramer3, Ed Lewis2, Drazen Raucher1, John J. Correia1.
1University of Mississippi Medical Center, Jackson, MS, USA, 2Mississippi State University, Starkville, MS, USA, 3Millsaps College, Jackson, MS, USA.
Abstract Body: Elastin-like Polypeptides (ELPs) are genetically engineered biopolymers that are derived from the endogenous protein Tropoelastin. ELPs are structurally disordered and soluble at low temperatures but transition to a β-spiral and aggregate at a Transition Temperature (TT). This aggregation is being explored as a novel drug delivery vector by thermally targeting systemically delivered ELP-drug conjugates. We are investigating the biophysical properties of ELP[V5G3A2-150] as a means of understanding and predicting the behavior in vivo. We have investigated the hydrodynamic, structural and thermodynamic properties of ELP[V5G3A2-150] through the use of CD, turbidity, DLS, DSC and SV. DLS and SV analyses suggest that ELP[V5G3A2-150] experiences small amounts of weak association below the TT that increase with temperature. CD analyses further indicate that below the TT ELP[V5G3A2-150] consists of both disordered (≈75%) and β-conformation (≈25%) and as the temperature and concentration is increased the % β-conformation increases. The temperature & concentration dependence of β-conformation suggests that the weak association can be attributed to heterogeneous β-sheets. SV revealed that above the TT ELP[V5G3A2-150] exhibits a temperature dependent critical concentration (CC). This CC is consistent with the TT and suggests that the TT may be described as a solubility constant.
Assembly in serum raises the TT by ≈ 2.5°C. This is opposite to the expected effect of macromolecular crowding and suggests that certain serum proteins may be associating with ELP[V5G3A2-150]. Investigation of this effect through SV was greatly complicated by the presence of the Johnston-Ogston (J-O) effect. Further investigation suggested additional complexity in systems exhibiting the J-O effect than previously reported. Two of the additional complexities already determined are cross-term hydrodynamic non-ideality and high-concentration convection. Additional research into the effects of attaching CPPs to ELP[V5G3A2-150] will be presented. Work supported by NSF ARRA 0959211 grant.
Commercial Relationship:  D. Lyons: None. V. Le: None. G.L. Bidwell: None. W. Kramer: None. E. Lewis: None. D. Raucher: None. J.J. Correia: None.



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