title: A blue-green absorbing cross-linker for rapid photoswitching of peptide helix content.
abstract: Azobenzene derivatives can be used to reversibly photoregulate secondary structure when introduced as intramolecular bridges in peptides and proteins. Here we report the design, synthesis, and characterization of a disubstituted N,N-dialkyl azobenzene derivative that absorbs near 480 nm in aqueous solution and relaxes with a half-life of approximately 50 ms at room temperature. The wavelength of maximum absorbance and the rate of thermal relaxation are solvent-dependent. An increase in the percentage of organic solvent leads, in general, to a blue shift in the absorbance maximum and a slowing of the relaxation rate. In accordance with the design, the thermal relaxation of the azobenzene cross-linker from cis to trans causes an increase in the helix content of one peptide where the linker is attached via cysteine residues spaced at i, i + 11 positions and a decrease in helix content of another peptide with cysteine residues spaced at i, i + 7. This cross-linker design thus expands the possibilities for fast photocontrol of peptide and protein structure.
authors.affiliation: Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, ON M5S 3H6, Canada.
authors.forename: Lei
authors.initials: L
authors.lastname: Chi
authors.forename: Oleg
authors.initials: O
authors.lastname: Sadovski
authors.forename: G Andrew
authors.initials: GA
authors.lastname: Woolley
mesh_terms: D003116:Color; D003432:Cross-Linking Reagents / Q000138:chemical synthesis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D010777:Photochemistry; D017433:Protein Structure, Secondary; D012997:Solvents; D013057:Spectrum Analysis; D013997:Time Factors
chemical_list: D003432:Cross-Linking Reagents; D010455:Peptides; D012997:Solvents