title: NMR spectroscopy of proteins encapsulated in a positively charged surfactant.
abstract: Traditionally, large proteins, aggregation-prone proteins, and membrane proteins have been difficult to examine by modern multinuclear and multidimensional solution NMR spectroscopy. A major limitation presented by these protein systems is that their slow molecular reorientation compromises many aspects of the more powerful solution NMR methods. Several approaches have emerged to deal with the various spectroscopic difficulties arising from slow molecular reorientation. One of these takes the approach of actively seeking to increase the effective rate of molecular reorientation by encapsulating the protein of interest within the protective shell of a reverse micelle and dissolving the resulting particle in a low viscosity fluid. Since the encapsulation is largely driven by electrostatic interactions, the preparation of samples of acidic proteins suitable for NMR spectroscopy has been problematic owing to the paucity of suitable cationic surfactants. Here, it is shown that the cationic surfactant CTAB may be used to prepare samples of encapsulated anionic proteins dissolved in low viscosity solvents. In a more subtle application, it is further shown that this surfactant can be employed to encapsulate a highly basic protein, which is completely denatured upon encapsulation using an anionic surfactant.
authors.affiliation: Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104-6059, USA.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Lefebvre
authors.forename: Weixia
authors.initials: W
authors.lastname: Liu
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Peterson
authors.forename: Kathleen G
authors.initials: KG
authors.lastname: Valentine
authors.forename: A Joshua
authors.initials: AJ
authors.lastname: Wand
mesh_terms: D000818:Animals; D002412:Cations; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000032:analysis* / Q000737:chemistry*; D045304:Cytochromes c / Q000032:analysis* / Q000737:chemistry*; D049452:Green Fluorescent Proteins / Q000032:analysis* / Q000737:chemistry*; D006736:Horses; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009206:Myocardium / Q000201:enzymology; D011506:Proteins / Q000032:analysis / Q000737:chemistry; D013048:Specimen Handling / Q000379:methods; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002412:Cations; D002593:Cetrimonium Compounds; D020099:Coated Materials, Biocompatible; D011506:Proteins; D013501:Surface-Active Agents; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D045304:Cytochromes c; D000077286:Cetrimonium