2‐Oxazoline Formation for Selective Chemical Labeling of 5‐Hydroxylysine |
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Authors: | Dr Gosuke Hayashi Ryosuke Sakamoto Prof Akimitsu Okamoto |
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Institution: | 1. Department of Chemistry and Biotechnology, The University of Tokyo, 7‐3‐1?Hongo, Bunkyo‐ku, Tokyo 113‐8656 (Japan);2. Research Center for Advanced Science and Technology, The University of Tokyo, 4‐6‐1?Komaba, Meguro‐ku, Tokyo 153‐8904 (Japan) |
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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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Keywords: | hydroxylysine oxazoline formation peptide labeling posttranslational modification proteomics |
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