Matrix-Assisted Laser Desorption/Ionization Fourier Transform Mass Spectrometry for the Identification of Orcokinin Neuropeptides in Crustaceans Using Metastable Decay and Sustained Off-Resonance Irra

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• 作者：Elizabeth A. Stemmler ; Heather L. Provencher ; Maureen E. Guiney ; Noah P. Gardner ; and Patsy S. Dickinson
• 刊名：Analytical Chemistry
• 出版年：2005
• 出版时间：June 1, 2005
• 年：2005
• 卷：77
• 期：11
• 页码：3594 - 3606
• 全文大小：324K
• 年卷期：v.77,no.11(June 1, 2005)
• ISSN：1520-6882

文摘

Vacuum UV matrix-assisted laser desorption/ionization(MALDI) Fourier transform ion cyclotron resonance massspectrometry (FTMS) has been applied to the directanalysis of crustacean neuronal tissues using in-cellaccumulation techniques to improve sensitivity. In anextension of previous work by Li and co-workers (Kutz,K. K.; Schmidt, J. J.; Li, L. Anal. Chem. 2004, 76,5630-5640), and with a focus on the Maine lobster,Homarus americanus, we report that many peaks appearing in direct tissue spectra from crustaceans resultfrom the metastable decay of aspartate-containing neuropeptides with localized protonation sites. We report onmass spectral characteristics of crustacean neuropeptidesunder MALDI-FTMS conditions and show how fragmentsformed by Asp-Xxx cleavages can be used to advantagefor the identification of orcokinin peptides, a ubiquitousfamily of crustacean neuropeptides with a highly conserved N-terminus sequence. We show that predictedfragment ion fingerprints (FIFs) can be used to screeninternally calibrated direct tissue spectra to provide high-confidence identification of previously identified orcokininpeptides. We use FIFs, identified based upon characteristic neutral losses, to screen for new members of theorcokinin family. Sustained off-resonance irradiation ofy-series fragment ions is used to sequence the variableC-terminus. We apply these techniques to the analysis ofCoG tissues from Cancer borealis and Panulirus interruptus and show that orcokinins in P. interruptuswere misidentified in a previous MALDI-TOF study.