期刊
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY
卷 203, 期 1-3, 页码 A1-A9出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/S1387-3806(00)00389-4
关键词
insulin; electrospray ionization; unimolecular dissociation; ion/ion reaction; quadrupole ion trap
Ion trap collisional activation is used to study the effects of charge state on protonated insulin decompositions for three forms of insulin: bovine, porcine, and human. Tandem mass spectrometry data are presented for ions with one to five protons dissociated under identical resonance excitation conditions. The (M+5H)(5+) and (M+4H)(4+) ions fragment exclusively by peptide bond cleavage of bonds outside the cycles formed by the disulfide linkages present in the insulin molecule, whereas the (M+3H)(3+) and (M+2H)(2+) ions appear to show a mixture of peptide bond cleavage and fragments arising from mechanisms associated with disulfide bond cleavage. The (M+H)(+) ion fragments almost exclusively by way of disulfide bond cleavage, with the only major exception being cleavage on the C-terminal side of glutamic acid residues external to the cycles formed by the disulfide linkages. (C) 2000 Elsevier Science B.V.
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