title: The design, synthesis, and initial evaluation of benzophenone-containing peptides as potential photoaffinity labels of oligosaccharyltransferase.
abstract: The benzophenone photophore was incorporated into protected tripeptides and tetrapeptides as photoactivatable probes to study the multimeric enzyme oligosaccharyltransferase (OST). These peptides contain the -Asn-X-Thr- sequon which is required for OST-catalyzed N-glycosylation. Two tripeptides, Bz-Asn-Bpa-Thr-NH2 (3b) and Bz-Asn-Lys[N epsilon-(4-Bz)Bz]-Thr-NH2 (4b), were found to be good OST substrates. They were competitive inhibitors versus standard peptide substrate [14C]Bz-Asn-Leu-Thr-NH2 and their Ki values were determined to be 41 +/- 6 microM and 21 +/- 6 microM, respectively, using synthetic (GlcNAc)2-PP-dolichol.
authors.affiliation: Department of Chemistry, College of Pharmacy, University of Michigan, Ann Arbor 48109, USA.
authors.forename: T
authors.initials: T
authors.lastname: Xu
authors.forename: H
authors.initials: H
authors.lastname: Khanna
authors.forename: J K
authors.initials: JK
authors.lastname: Coward
mesh_terms: D001577:Benzophenones / Q000737:chemistry*; D006602:Hexosyltransferases; D008565:Membrane Proteins; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D019920:Photoaffinity Labels / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D014166:Transferases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001577:Benzophenones; D008565:Membrane Proteins; D010455:Peptides; D019920:Photoaffinity Labels; C047723:benzophenone; D014166:Transferases; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase