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Show UNDERGRADUATE RESEARCH ABSTRACTS SPRING 2007 lark b, Uqilvie Peter Flynn Properties of Encapsulated Proteins in Mg(A0T)2 and NaAOT Mark E. Ogilvie (Peter Flynn) Department of Chemistry University of Utah Gramicidin A (gA), a homodimer, pore forming ion channel membrane protein was encapsulated in a varietJ of surfactants, including; Magnesium bis(2-ethylhexyl)sulfosuccinate Mg(AOT)2, hexadecyltrimethylammoni-l urn bromide (CTAB), hexadecyltrimethylammonium bromide (DTAB), and a mixed surfactant 70:30 sodium bis(2-ethylhexyl)sulfosuccinate (NaAOT):C12E4Tetraethylene glycol monododecyl ether (C12E4). Subsequent studies using solution NMR techniques namely 1 H 1 D and diffusion coefficient experiments were performed on a solution of 50mM Mg(AOT)2 with a 4mM concentration of gramicidin A in TFE and water loading, wO, equal to zero. Early analysis of these experiments has revealed that gramicidin A experi- I ences a structural perturbation in Mg(AOT)2 compared to NaAOT and other mimetics. It is plausible that reverse micelles mimic a plasma membrane and thus permit membrane proteins to be encapsulated. Also, Ubiquitin, a protein, was encapsulated within a reverse micelle of NaAOT and is currently being studiedj using solution 15N HSQC NMR. Lanthanides possess paramagnetical character and form tensors causing anisotropic tumbling. In the current study, Yb(N03)3 will be added to a 10OmM NaAOT solution in pentane with a water loading of approximately 20 and a concentration of 1 mM Yb3+ such that 1 Yb3+ metal ion is housed within a reverse micelle (assuming an aggregation number of 100). Most likely the lanthanide will reside near the sulfonate head of AOT-. Previous studies of membrane proteins using NMR and lanthanides have involved encapsulating proteins in micelles and having membrane proteins with lanthanide binding sites that when bound by a lanthanide are weakly aligned enabling the measurement of residual dipolar coupling (RDC), which provide angular constraints for the determination of the tertiary structures of membrane proteins. 53 |