title: Bromine isotopic signature facilitates de novo sequencing of peptides in free-radical-initiated peptide sequencing (FRIPS) mass spectrometry.
abstract: We recently showed that free-radical-initiated peptide sequencing mass spectrometry (FRIPS MS) assisted by the remarkable thermochemical stability of (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) is another attractive radical-driven peptide fragmentation MS tool. Facile homolytic cleavage of the bond between the benzylic carbon and the oxygen of the TEMPO moiety in o-TEMPO-Bz-C(O)-peptide and the high reactivity of the benzylic radical species generated in •Bz-C(O)-peptide are key elements leading to extensive radical-driven peptide backbone fragmentation. In the present study, we demonstrate that the incorporation of bromine into the benzene ring, i.e. o-TEMPO-Bz(Br)-C(O)-peptide, allows unambiguous distinction of the N-terminal peptide fragments from the C-terminal fragments through the unique bromine doublet isotopic signature. Furthermore, bromine substitution does not alter the overall radical-driven peptide backbone dissociation pathways of o-TEMPO-Bz-C(O)-peptide. From a practical perspective, the presence of the bromine isotopic signature in the N-terminal peptide fragments in TEMPO-assisted FRIPS MS represents a useful and cost-effective opportunity for de novo peptide sequencing.
authors: Department of Chemistry, Sogang University, Seoul, 121-742, Korea.
authors: Jungjoo
authors: J
authors: Nam
authors: Hyuksu
authors: H
authors: Kwon
authors: Inae
authors: I
authors: Jang
authors: Aeran
authors: A
authors: Jeon
authors: Jingyu
authors: J
authors: Moon
authors: Sun Young
authors: SY
authors: Lee
authors: Dukjin
authors: D
authors: Kang
authors: Sang Yun
authors: SY
authors: Han
authors: Bongjin
authors: B
authors: Moon
authors: Han Bin
authors: HB
authors: Oh
mesh_terms: D001966:Bromine / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D005609:Free Radicals / Q000737:chemistry; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D020539:Sequence Analysis, Protein / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014357:Trypsin
chemical_list: D005609:Free Radicals; D010446:Peptide Fragments; D014357:Trypsin; D001966:Bromine
keywords: bromine signature; de novo sequencing; free-radical-initiated peptide sequencing (FRIPS); isotopic pattern; radical-based tandem mass spectrometry