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Analysis of oxidation process of cholecystokinin octapeptide with reactive oxygen species by high‐performance liquid chromatography and subsequent electrospray ionization mass spectrometry
Author(s) -
Ichiba Hideaki,
Nakamoto Mio,
Yajima Takehiko,
Takayama Mitsuo,
Fukushima Takeshi
Publication year - 2010
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.1262
Subject(s) - chemistry , chromatography , electrospray ionization , mass spectrometry , electrospray , sample preparation in mass spectrometry , direct electron ionization liquid chromatography–mass spectrometry interface , liquid chromatography–mass spectrometry , extractive electrospray ionization , ionization , chemical ionization , ion , organic chemistry
The C ‐terminal octapeptide of cholecystokinin (CCK8) includes some easily oxidizable amino acids. The oxidation of CCK8 by reactive oxygen species (ROS) such as hydrogen peroxide (H 2 O 2 ) and hydroxyl radicals (OH • ) was investigated using reversed‐phase high performance liquid chromatography (RP‐HPLC) and subsequent electrospray ionization mass spectrometry. The mechanism of oxidation of CCK8 in the H 2 O 2 system differed from that of CCK8 in the Fenton system, in which OH • are produced. In the H 2 O 2 system, 28 Met and 31 Met were oxidized to methionine sulfoxide, and no further oxidation or degradation/hydrolysis occurred. On the other hand, in the Fenton system, 28 Met and 31 Met residues were oxidized to methionine sulfone via the formation of methionine sulfoxide. In addition, the oxidized product was observed at the Trp residue but not at the Tyr residue, and small peptide fragments from CCK8 were observed in the Fenton system. From these results, it was concluded that 28 Met and 31 Met residues of CCK8 are susceptible to oxidation by ROS. Copyright © 2009 John Wiley & Sons, Ltd.