Electron transfer dissociation mass spectromerty studies of peptides

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dc.contributor Szulczewski, Gregory J.
dc.contributor Busenlehner, Laura S.
dc.contributor Woski, Stephen A.
dc.contributor Kim, Yonghyun
dc.contributor.advisor Cassady, Carolyn J.
dc.contributor.author Feng, Changgeng
dc.date.accessioned 2017-03-01T17:21:49Z
dc.date.available 2017-03-01T17:21:49Z
dc.date.issued 2014
dc.identifier.other u0015_0000001_0001776
dc.identifier.other Feng_alatus_0004D_12103
dc.identifier.uri https://ir.ua.edu/handle/123456789/2222
dc.description Electronic Thesis or Dissertation
dc.description.abstract Electron transfer dissociation (ETD) is an important tandem mass spectrometry technique in peptide and protein sequencing. In the past, ETD experiments have primarily involved basic peptides. A limitation of ETD is the requirement that analytes be at least doubly cationized by electrospray ionization (ESI). In this research, a method has been developed for enhancing protonation of acidic and neutral peptides. This has allowed doubly protonated ions, [M+2H]2+, to be produced from peptides without basic residues and has enabled their study by ETD. This dissertation includes the first extensive study of non-basic peptides by ETD. The effects of a basic residue on ETD were investigated using a series of heptapeptides with one lysine, histidine, or arginine residue. The spectra contain primarily c"- and z'-ions, which result from cleavage of N-C_α bonds along the backbone. Almost all of product ions include the basic residue. Enhanced fragmentation occurs on the C-terminal side of the basic residue. Also, cn-1 formation is enhanced, where n is the number of residues in the peptide. Addition of Cr(III) nitrate to a solution of the neutral peptide heptaalanine yields abundant [M+2H]2+ formation by ESI. Eleven metal ions were tested and Cr(III) gave by far the most intense supercharging of peptides. In contrast, Cr(III) does not increase protonation of proteins. Experiments were performed to explore the supercharging mechanism. Addition of Cr(III) to the sample solution was used to produce [M+2H]2+ in the remainder of this research. Neutral peptides with alkyl side chains were studied by ETD and found to produce b- and c-ions. Two mechanisms are proposed for b-ion formation, which involves cleavage of backbone amide (O=C)-N bonds. The length of peptide chain affects ETD fragmentation, but the identity of the alkyl residue has minimal effect. Acidic peptides with one or two aspartic or glutamic acid residues produce b-, c- and zOe-ions. The mechanism of b-ion formation is probably the same as that for neutral peptides, while c- and zOe-ions result from a radical mechanism involving oxygen atoms on the acidic side chains. For highly acidic heptapeptides, c- and zOe-ions are the major products, which supports a radical mechanism.
dc.format.extent 171 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Chemistry
dc.subject.other Analytical chemistry
dc.title Electron transfer dissociation mass spectromerty studies of peptides
dc.type thesis
dc.type text
etdms.degree.department University of Alabama. Department of Chemistry
etdms.degree.discipline Chemistry
etdms.degree.grantor The University of Alabama
etdms.degree.level doctoral
etdms.degree.name Ph.D.

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