title: Secondary structure and topology of a mitochondrial presequence peptide associated with negatively charged micelles. A 2D H-NMR study.
abstract: In this study the secondary structure and topology of the peptide, corresponding to the presequence of cytochrome oxidase subunit IV (p25) in a negatively charged membrane-mimetic environment, were assessed by circular dichroism and two-dimensional nuclear magnetic resonance. The micelles used consisted of dodecylphosphoglycol (DPG), a mild anionic detergent with a headgroup resembling that of phosphatidylglycerol. The secondary structure was analyzed by interresidue nuclear Overhauser enhancement measurements and chemical shifts of backbone protons. The data revealed alpha-helix formation of the peptide upon interaction with the micelles, both in the N- and in the C-terminal halves, which are separated from each other by the proline residue at position 13. The topology of the peptide was studied by determining the effect of spin-labeled 12-doxylstearate on the line widths of the peptide proton resonances. This method revealed the insertion of hydrophobic residues of both the N- and the C-terminal halves of p25 into the hydrophobic environment of the micelles, demonstrating the orientation of the amphiphilic helix.
authors.affiliation: Department of Biochemistry of Membranes, Institute of Biomembranes, Utrecht University, The Netherlands.
authors.forename: V
authors.initials: V
authors.lastname: Chupin
authors.forename: J M
authors.initials: JM
authors.lastname: Leenhouts
authors.forename: A I
authors.initials: AI
authors.lastname: de Kroon
authors.forename: B
authors.initials: B
authors.lastname: de Kruijff
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D003497:Cyclic N-Oxides; D003576:Electron Transport Complex IV / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008928:Mitochondria / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry; D021382:Protein Sorting Signals / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013113:Spin Labels; D015003:Yeasts / Q000201:enzymology*
chemical_list: D003497:Cyclic N-Oxides; D008823:Micelles; D010743:Phospholipids; D021382:Protein Sorting Signals; D013113:Spin Labels; C098540:dodecylphosphoglycol; C037404:12-doxylstearic acid; D003576:Electron Transport Complex IV