Investigation of bn-44 Peptide Fragments Using High Resolution Mass Spectrometry and Isotope Labeling

An N-terminal deuterohemin-containing hexapeptide (DhHP-6) was designed as a short peptide cytochrome c (Cyt c ) mimetic to study the effect of N-terminal charge on peptide fragmentation pathways. This peptide gave different dissociation patterns than normal tryptic peptides. Upon collision-induced...

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Published inJournal of the American Society for Mass Spectrometry Vol. 25; no. 12; pp. 2116 - 2124
Main Authors Wang, Bing, Yu, Jiayi, Wang, Huixin, Wei, Zhonglin, Guo, Xinhua, Xiao, Zhaohui, Zeng, Zhoufang, Kong, Wei
Format Journal Article
LanguageEnglish
Published Boston Springer US 01.12.2014
Subjects
Analytical Chemistry
Bioinformatics
Biotechnology
Chemistry
Chemistry and Materials Science
Cytochromes c - chemistry
Hemin - analogs & derivatives
Hemin - chemistry
Ions - chemistry
Isotope Labeling - methods
Oligopeptides - chemistry
Organic Chemistry
Peptide Fragments - chemistry
Proteomics
Research Article
Tandem Mass Spectrometry - methods
Charge-remote fragmentation
b
Deuterohemin
44 ions
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Summary:An N-terminal deuterohemin-containing hexapeptide (DhHP-6) was designed as a short peptide cytochrome c (Cyt c ) mimetic to study the effect of N-terminal charge on peptide fragmentation pathways. This peptide gave different dissociation patterns than normal tryptic peptides. Upon collision-induced dissociation (CID) with an ion trap mass spectrometer, the singly charged peptide ion containing no added proton generated abundant and characteristic b n -44 ions instead of b n -28 (a n ) ions. Studies by high resolution mass spectrometry (HRMS) and isotope labeling indicate that elimination of 44 Da fragments from b ions occurs via two different pathways: (1) loss of CH 3 CHO (44.0262) from a Thr side chain; (2) loss of CO 2 (43.9898) from the oxazolone structure in the C-terminus. A series of analogues were designed and analyzed. The experimental results combined with Density Functional Theory (DFT) calculations on the proton affinity of the deuteroporphyrin demonstrate that the production of these novel b n -44 ions is related to the N-terminal charge via a charge-remote rather than radical-directed fragmentation pathway. Graphical Abstract ᅟ
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ISSN:1044-0305
1879-1123
DOI:10.1007/s13361-014-0994-9