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Sequence information, distinction and quantitation of C ‐terminal leucine and isoleucine in ternary complexes of tripeptides with Cu(II) and 2,2′‐bipyridine
Author(s) -
Vaisar Tomáš,
Gatlin Christine L.,
Rao Ramesh D.,
Seymour Jennifer L.,
Tureček František
Publication year - 2001
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.135
Subject(s) - chemistry , tripeptide , peptide , electrospray ionization , isoleucine , leucine , amino acid , peptide sequence , stereochemistry , crystallography , mass spectrometry , chromatography , biochemistry , gene
Tripeptides form ternary complexes with Cu 2+ and 2,2′‐bipyridine (bpy) that self‐assemble upon mixing the components in aqueous methanol solution. Electrospray ionization (ESI) of the complex solutions provides abundant singly charged [Cu(peptide − H)bpy] + and doubly charged [Cu(peptide)bpy] 2+ ions. Collision‐induced dissociation (CID) at low ion kinetic energies of several tripeptides, AGG, GGA, LGG, GGL, GGI, FGG, GGF, LGF, GLF, GFL, GYA and GAY, showed fragments that were indicative of the amino acid sequence in the peptide. In addition, CID of single and doubly charged complexes of isomeric tripeptides GGL and GGI provided unambiguous distinction of the isomeric leucine and isoleucine residues. Leucine peptides eliminated C 3 H 7 radicals from the amino acid side‐chain whereas isoleucine eliminated C 2 H 5 radicals. CID of gas‐phase doubly charged peptide complexes in a quadrupole ion trap produced a series of singly charged sequence fragments that following isolation and further CID furnished distinct fragments that allowed quantitation of leucine and isoleucine‐containing peptides in mixtures. Copyright © 2001 John Wiley & Sons, Ltd.