title: Refractive index matching to develop transparent polyaphrons: Characterization of immobilized proteins.
abstract: Refractive index matching was used to create optically transparent polyaphrons to enable proteins adsorbed to the aphron surface to be characterized. Due to the significant light scattering created by polyaphrons, refractive index matching allowed for representative circular dichroism (CD) spectra and acceptable structural characterization. The method utilized n-hexane as the solvent phase, a mixture of glycerol and phosphate buffer (30% [w/v]) as the aqueous phase, and the non-ionic surfactants, Laureth-4 and Kolliphor P-188. Deconvolution of CD spectra revealed that the immobilized protein adapted its native conformation, showing that the adsorbed protein interacted only with the bound water layer ("soapy shell") of the aphron. Isothermal calorimetry further demonstrated that non-ionic surfactant interactions were virtually non-existent, even at the high concentrations used (5% [w/v]), proving that non-ionic surfactants can preserve protein conformation.
authors.affiliation: Department of Chemical Engineering, Imperial College London, SW7 2AZ London, UK. Electronic address: keeran.ward10@ic.ac.uk.
authors.forename: Keeran
authors.initials: K
authors.lastname: Ward
authors.affiliation: Department of Chemical Engineering, Imperial College London, SW7 2AZ London, UK. Electronic address: d.stuckey@ic.ac.uk.
authors.forename: David C
authors.initials: DC
authors.lastname: Stuckey
mesh_terms: D000818:Animals; D002021:Buffers; D002417:Cattle; D002645:Chickens; D002918:Chymotrypsin / Q000737:chemistry*; D002942:Circular Dichroism; D005990:Glycerol / Q000737:chemistry; D006586:Hexanes / Q000737:chemistry; D055767:Immobilized Proteins / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry*; D010047:Ovalbumin / Q000737:chemistry*; D000077423:Polidocanol; D011092:Polyethylene Glycols / Q000737:chemistry; D011487:Protein Conformation; D012031:Refractometry; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012996:Solutions; D012997:Solvents / Q000737:chemistry
chemical_list: D002021:Buffers; D006586:Hexanes; D055767:Immobilized Proteins; D012996:Solutions; D012997:Solvents; D000077423:Polidocanol; D012710:Serum Albumin, Bovine; C026385:n-hexane; D011092:Polyethylene Glycols; D010047:Ovalbumin; D009113:Muramidase; D002918:Chymotrypsin; C117608:alpha-chymotrypsin; D005990:Glycerol
keywords: Adsorption; Colloidal liquid aphrons (CLAs); Conformation; Immobilization; Protein; Refractive index matching