title: Gold nanoparticle-cytochrome C complexes: the effect of nanoparticle ligand charge on protein structure.
abstract: We report the effect of nanoparticle ligand charge on the structure of a covalently, site-specifically linked protein. Au nanoparticles with positive, negative, and neutral ligands were appended to a specific cysteine, C102, of Saccharomyces cerevisiae cytochrome c. Conjugates were purified by HPLC or gel electrophoresis. Circular dichroism spectroscopy shows that changing the nanoparticle ligand dramatically influences the attached cytochrome c structure. The protein retains its structure with neutral ligands but denatures in the presence of charged species. This is rationalized by the electrostatic interaction of amino acids in the local vicinity of C102 with the endgroups of the ligand.
authors.affiliation: Department of Mechanical Engineering and the Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Aubin-Tam
authors.forename: Kimberly
authors.initials: K
authors.lastname: Hamad-Schifferli
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D045304:Cytochromes c / Q000737:chemistry*; D004587:Electrophoresis, Agar Gel; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011487:Protein Conformation
chemical_list: D008024:Ligands; D006046:Gold; D045304:Cytochromes c