title: Effect of pegylation on the structure and function of horse cytochrome c.
abstract: The preparation and spectrophotometric characterization of (both Fe2+ and Fe3+ forms) poly(ethylene glycol) (PEG; av FW 5000)-modified horse cytochrome c (cyt c(PEG)n) with different degrees of modification (nav = 6, 19) by UV-vis spectroscopy, circular dichroism spectroscopy, resonance Raman spectroscopy, and cyclic voltammetry are described. Extensive modification (nav = 19) of cyt c causes gross structural deformation of the heme as evidenced by major spectral changes in the UV-vis and circular dichroism spectral signatures of both the Fe2+ and Fe3+ forms. Modification of cyt c by six PEG residues, however, produces a protein in which the heme active site is structurally and functionally intact (UV-vis, circular dichroism, and resonance Raman) and which exhibits at least quasireversible direct electron transfer (Eo' = 338 +/- 5 mV vs SHE; (2.1 +/- 0.6) x 10(-3) cm/s) at bis(4-pyridyl) disulfide-modified Au electrodes.
authors.affiliation: Department of Chemistry, Northeastern University, Boston, Massachusetts 02115.
authors.forename: P A
authors.initials: PA
authors.lastname: Mabrouk
mesh_terms: D000818:Animals; D002942:Circular Dichroism; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism; D004563:Electrochemistry; D006736:Horses; D066298:In Vitro Techniques; D015394:Molecular Structure; D011092:Polyethylene Glycols; D012996:Solutions; D013057:Spectrum Analysis; D013059:Spectrum Analysis, Raman; D014867:Water
chemical_list: D003574:Cytochrome c Group; D012996:Solutions; D014867:Water; D011092:Polyethylene Glycols