2013年12月
Simultaneous ultraviolet B-induced photo-oxidation of tryptophan/tyrosine and racemization of neighboring aspartyl residues in peptides
FREE RADICAL BIOLOGY AND MEDICINE
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- 巻
- 65
- 号
- 開始ページ
- 1037
- 終了ページ
- 1046
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1016/j.freeradbiomed.2013.08.171
- 出版者・発行元
- ELSEVIER SCIENCE INC
Although proteins consist exclusively of L-amino acids, it is well known that a-isomers of aspartyl (Asp) residues occur at specific sites in lens crystallins of elderly people with cataracts. The presence of a-isomers is thought to result from the racemization of Asp residues in the crystallins during aging. It has been reported that this racemization progresses owing to UV-B exposure; however, the underlying mechanism remains unknown because Asp is not a photosensitive residue because there is no aromatic group in its chemical structure. In this study, we synthesized peptides in which the residue neighboring the Asp was the photosensitive residue tryptophan (Trp) or tyrosine (Tyr). After exposing these peptides to UV-B, we used RP-HPLC to confirm that racemization of Asp residues occurred in peptides in which a Trp or Tyr residue was inserted near the Asp; simultaneously, several varieties of photoproducts derived from Trp and Tyr were detected by mass spectroscopy. Promotion of the racemization of Asp residues in peptides with a neighboring Trp was much more significant than in those with Tyr. In particular, when Trp was next to an Asp residue on the C-terminal side of the peptide, the racemization reaction was accelerated. (C) 2013 Elsevier Inc. All rights reserved.
- リンク情報
- ID情報
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- DOI : 10.1016/j.freeradbiomed.2013.08.171
- ISSN : 0891-5849
- eISSN : 1873-4596
- PubMed ID : 23999504
- Web of Science ID : WOS:000328868900098