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Updated: Apr 16, 2026

Enzymatic Cascade Reactions for the Synthesis of Chiral Amino Alcohols from L-lysine
Published on: February 16, 2018
2-Oxazoline formation for selective chemical labeling of 5-hydroxylysine
Gosuke Hayashi1, Ryosuke Sakamoto, Akimitsu Okamoto
1Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan).
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.
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