title: 2-Oxazoline formation for selective chemical labeling of 5-hydroxylysine.
abstract: Hydroxylation of lysine, one of posttranslational modifications of proteins, generates 5-hydroxylysine (Koh) and plays a crucial role in regulating protein functions in cellular activity. We have developed a chemical labeling method of Koh. The 1,2-aminoalcohol moiety of Koh in synthetic peptide sequences was trapped by an alkyne-containing benzimidate to form a 2-oxazoline ring. An additional ammonia treatment process removed the undesirable amidine residue formed between benzimidate and lysine. During the ammonia treatment, the oxazoline residue formed at Koh mainly remained intact, and the ring opening to the amide form was observed for only part of oxazoline, indicating that the chemical labeling is amino acid selective. Azide-substituted biotin or fluorescent dye was attached to the peptide through Huisgen cycloaddition at Koh and converted into an alkyne-labeled oxazoline form. The Koh-labeling assay could provide a platform to enhance proteomic research of lysine hydroxylation.
authors.affiliation: Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan).
authors.forename: Gosuke
authors.initials: G
authors.lastname: Hayashi
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Sakamoto
authors.forename: Akimitsu
authors.initials: A
authors.lastname: Okamoto
mesh_terms: D006901:Hydroxylysine / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D015394:Molecular Structure; D010080:Oxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D040901:Proteomics; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D010080:Oxazoles; D006901:Hydroxylysine
keywords: hydroxylysine; oxazoline formation; peptide labeling; posttranslational modification; proteomics