Monoisotopic Mass Determination Algorithm for Selenocysteine-Containing Polypeptides from Mass Spectrometric Data Based on Theoretical Modeling of Isotopic Peak Intensity Ratios

Title
Monoisotopic Mass Determination Algorithm for Selenocysteine-Containing Polypeptides from Mass Spectrometric Data Based on Theoretical Modeling of Isotopic Peak Intensity Ratios
Author(s)
김화영이선호[이선호]박건수[박건수]나승진[나승진]백은옥[백은옥]박형서[박형서]박희진[박희진]이공주[이공주]정재호[정재호]김진욱[김진욱]
Keywords
SELENOPROTEIN-P; IDENTIFICATION; THIOREDOXIN; DISELENIDE; MECHANISMS; REDUCTASES; FAMILY
Issue Date
201209
Publisher
AMER CHEMICAL SOC
Citation
JOURNAL OF PROTEOME RESEARCH, v.11, no.9, pp.4488 - 4498
Abstract
Selenoproteins, containing selenocysteine (Sec, U) as the 21st amino acid in the genetic code, are well conserved from bacteria to human, except yeast and higher plants that miss the Sec insertion machinery. Determination of Sec association is important to find substrates and to understand redox action of selenoproteins. While mass spectrometry (MS) has become a common and powerful tool to determine an amino acid sequence of a protein, identification of a protein sequence containing Sec was not easy using MS because of the limited stability of Sec in selenoproteins. Se has six naturally occurring isotopes, Se-74, Se-76, Se-77, Se-78, Se-80, and Se-82, and Se-80 is the most abundant isotope. These characteristics provide a good indicator for selenopeptides but make it difficult to detect selenopeptides using software analysis tools developed for common peptides. Thus, previous reports verified MS scans of selenopeptides by manual inspection. None of the fully automated algorithms have taken into account the isotopes of Se, leading to the wrong interpretation for selenopeptides. In this paper, we present an algorithm to determine monoisotopic masses of selenocysteine-containing polypeptides. Our algorithm is based on a theoretical model for an isotopic distribution of a selenopeptide, which regards peak intensities in an isotopic distribution as the natural abundances of C, H, N, O, S, and Se. Our algorithm uses two kinds of isotopic peak intensity ratios: one for two adjacent peaks and another for two distant peaks. It is shown that our algorithm for selenopeptides performs accurately, which was demonstrated with two LC-MS/MS data sets. Using this algorithm, we have successfully identified the Sec-Cys and Sec-Sec cross-linking of glutaredoxin 1 (GRX1) from mass spectra obtained by UPLC-ESI-q-TOF instrument.
URI
http://hdl.handle.net/YU.REPOSITORY/27284http://dx.doi.org/10.1021/pr300232y
ISSN
1535-3893
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의과대학 > 생화학.분자생물학교실 > Articles
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