title: Site-specific binding of quinones to proteins through thiol addition and addition-elimination reactions.
abstract: Ubiquinone-0, menaquinone-0, and 2,3,5-trimethyl-1,4-benzoquinone were site-specifically bound to free cysteine of proteins (yeast iso-1 cytochrome c as a model protein) through thioether bond formation. Model thioether quinone conjugates showed unexpected reactivity to cysteine of proteins as their parent quinones by thiol addition-elimination reaction. Cyclic voltammetry studies of the model compounds showed only minor differences in their redox potentials as compared to their parent quinones. Thioether ligation provides a general, simple, and fast method to construct model quinone protein systems. In addition, these studies also contribute to the understanding of biological activities, toxicity, and anti-cancer mechanism of quinones and thioether quinone adducts.
authors.affiliation: Institut für Biologie II/Biochemie, Schänzlestrasse 1, D-79104 Freiburg, Germany. wenwu.li@biologie.uni-freiburg.de
authors.forename: Wen-Wu
authors.initials: WW
authors.lastname: Li
authors.forename: Jürgen
authors.initials: J
authors.lastname: Heinze
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Haehnel
mesh_terms: D000595:Amino Acid Sequence; D016227:Benzoquinones / Q000737:chemistry / Q000378:metabolism; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism*; D004563:Electrochemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011809:Quinones / Q000737:chemistry* / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism; D024483:Vitamin K 3 / Q000737:chemistry / Q000378:metabolism
chemical_list: D016227:Benzoquinones; D010446:Peptide Fragments; D011809:Quinones; D013438:Sulfhydryl Compounds; C109863:ubiquinone-O; D024483:Vitamin K 3; D045304:Cytochromes c