title: cis/trans photoisomerization of secondary thiopeptide bonds.
abstract: The reversible cis/trans photoisomerization of secondary thiopeptide bonds has been systematically studied with UV-visible absorption, capillary electrophoresis, 1H NMR spectroscopy, and circular dichroism methods. It was found that the concentration of the cis conformers could be increased from less than 1 % in the thermal equilibrated solution to up to 20 % in the photostationary state. The rotational barriers of the thiopeptide bond and the pH dependence of the isomerization rates were also studied. The quantum yields of the trans-->cis and the cis-->trans processes were determined from photokinetic analysis.
authors.affiliation: Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle/Saale, Germany. j.zhao@bath.ac.uk
authors.forename: Jianzhang
authors.initials: J
authors.lastname: Zhao
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Micheau
authors.forename: Carolyn
authors.initials: C
authors.lastname: Vargas
authors.forename: Cordelia
authors.initials: C
authors.lastname: Schiene-Fischer
mesh_terms: D006863:Hydrogen-Ion Concentration; D010455:Peptides / Q000737:chemistry*; D010777:Photochemistry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013457:Sulfur Compounds / Q000737:chemistry*
chemical_list: D010455:Peptides; D013457:Sulfur Compounds