Fragmentation of tunichrome Sp-1 is dominated by an unusual gas-phase intramolecular rearrangement.
Fragmentation of tunichrome Sp-1 is dominated by an unusual gas-phase intramolecular rearrangement.
复制标题
Tunichrome Sp-1 的断裂主要由不寻常的气相分子内重排决定。
DOI：
10.1002/jms.530
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Craig,AGrey
中科院分区：
文献类型：
--
作者：
Taylor,StevenW;Kassel,DanielB;Tincu,JAndy;Craig,AGrey
TunichromeSp‐1is a modified pentapeptide from the ascidianStyela plicata, having the structure H‐DOPA‐DOPA‐Gly‐Pro‐dcΔDOPA (where DOPA = 3,4‐dihydroxyphenylalanine and dcΔDOPA = decarboxy‐(E)‐α,β‐dehydro‐DOPA). The tandem mass spectrum of the peptide is dominated by a number of abundant fragment ions that involve a gas‐phase rearrangement where the dcΔDOPA group becomes covalently attached to the N‐terminus. The high degree of rearrangement inSp‐1compared with a related octapeptide, plicatamide, allowed for detailed multiple mass spectrometric (MSn) (up ton= 6) experiments, and hence permitted a detailed assessment of the origin and routes to the formation of the various rearrangement ions. Analyses on both a triple‐quadrupole and a quadrupole time‐of‐flight mass spectrometer were made to ascertain whether the gas‐phase rearrangements observed for tunichromeSp‐1were unique to an ion trap mass spectrometer (i.e. the hypothesis being that perhaps the extended trapping times were required to facilitate this unusual gas‐phase rearrangement). Interestingly, analyses on both the triple‐quadrupole and quadruple time‐of‐flight mass spectrometers revealed an identical phenomenon, with the rearrangement fragment ions present at approximately the same abundance as the non‐rearranged a‐, b‐ and y‐type sequence ions. We suggest that the smaller size of tunichromeSp‐1compared with plicatamide facilitates the transfer of the dcΔDOPA group in this gas‐phase rearrangement. This rearrangement was not observed for peptide analogs of tunichromeSp‐1that did not contain the dcΔDOPA at the C‐terminus, confirming that the presence of dcΔDOPA is critical for the rearrangement. Copyright © 2003 John Wiley & Sons, Ltd.
