Combined Electron Transfer Dissociation鈥揅ollision-Induced Dissociation Fragmentation in the Mass Spectrometric Distinction of Leucine, Isoleucine, and Hydroxyproline Residues in Peptide Natural Produc

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• 作者：Kallol Gupta ; Mukesh Kumar ; Krishnappa Chandrashekara ; Kozhalmannom S. Krishnan ; Padmanabhan Balaram
• 刊名：Journal of Proteome Research
• 出版年：2012
• 出版时间：February 3, 2012
• 年：2012
• 卷：11
• 期：2
• 页码：515-522
• 全文大小：323K
• 年卷期：v.11,no.2(February 3, 2012)
• ISSN：1535-3907

文摘

Distinctions between isobaric residues have been a major challenge in mass spectrometric peptide sequencing. Here, we propose a methodology for distinction among isobaric leucine, isoleucine, and hydroxyproline, a commonly found post-translationally modified amino acid with a nominal mass of 113 Da, through a combined electron transfer dissociation鈥揷ollision-induced dissociation approach. While the absence of c and z^鈥?/i> ions, corresponding to the Yyy-Xxx (Xxx = Leu, Ile, or Hyp) segment, is indicative of the presence of hydroxyproline, loss of isopropyl (螖m = 43 Da) or ethyl radicals (螖m = 29 Da), through collisional activation of z radical ions, are characteristic of leucine or isoleucine, respectively. Radical migration processes permit distinctions even in cases where the specific z^鈥?/i> ions, corresponding to the Yyy鈥揕eu or 鈭扞le segments, are absent or of low intensity. This tandem mass spectrometric (MSⁿ) method has been successfully implemented in a liquid chromatography鈥揗Sⁿ platform to determine the identity of 23 different isobaric residues from a mixture of five different peptides. The approach is convenient for distinction of isobaric residues from any crude peptide mixture, typically encountered in natural peptide libraries or proteomic analysis.

Keywords:

isobaric amino acids; electron transfer dissociation; z^鈥?/i> ions; collision-induced dissociation; peptaibols; Conus peptides; wasp venom peptides