The McLafferty rearrangement in the Glu residue in a cyclic lipopeptide determined by Q-TOF MS/MS.
The intraresidue rearrangement and loss of the side chain of the Glu residue was found through MS/MS analysis of both original and methanol-esterified lipopeptides. Both Glu and Asp residues in the cyclic lipopeptide were esterified. The MS/MS results showed that the loss of fragment 72 or 86 was induced by McLafferty-type rearrangement from the Glu or esterified Glu. The mechanism of loss of the Glu residue can be used to determine or to corroborate the existence of the Glu and to help understand the fragment formation in MS/MS. The cleavage mechanism and m/z intensities imply that the sodium ion was easier attached and the cleavage would easily occur at specific sites.
Yang
Shi-Zhong
SZ
State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
Liu
Xiang-Yang
XY
Mu
Bo-Zhong
BZ
D001224:Aspartic Acid / Q000737:chemistry; D005973:Glutamine / Q000737:chemistry*; D055666:Lipopeptides / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D053719:Tandem Mass Spectrometry / Q000379:methods
D055666:Lipopeptides; D010456:Peptides, Cyclic; D005973:Glutamine; D001224:Aspartic Acid