Top-Down Analysis of the B-Subunit of Shiga Toxin from Escherichia coli using MALDI-TOF-TOF Mass Spectrometry: Asparagine and the Aspartic Acid Effect Mechanism
Clifton K. Fagerquist and William J. Zaragoza Agricultural Research Service, U.S. Department of Agricultural, Albany, CA
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Clifton Fagerquist (Presenter) Agricultural Research Service, WRRC, USDA
Presenter Bio: Dr. Clifton K. Fagerquist received his PhD in physical chemistry from UCLA in 1994 where he used fast atom bombardment and sector-field mass spectrometry to study stable and metastable gas phase clusters. After post-doctoral research at UC Berkeley and two years directing a mass spectrometry facility at University of Minnesota, Minneapolis, he joined the Agricultural Research Service (ARS) in Philadelphia. After two years in Philadelphia, he transferred to the ARS facility in Albany, California where he has been using advanced mass spectrometry and proteomic techniques to identify and characterize foodborne pathogens and their toxins.
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Abstract
We have examined the dissociation of Shiga toxin B-subunits expressed by Shiga toxin-producing Escherichia coli using MALDI-TOF-TOF mass spectrometry. In addition to polypeptide backbone cleavage on the C-terminal side of aspartic acid (D) and glutamic acid (E) residues consistent with the aspartic acid effect mechanism, we also observe cleavage on the C-terminal side of asparagine (N) residues. This fragmentation channel presents unique challenges for top-down proteomic identification if it is necessary to distinguish slight differences in polypeptide sequence, e.g. D ↔ N substitution.
= Discovery stage. (17.55%, 2019 US)
= Translation stage. (42.72%, 2019 US)
= Clinically available. (39.74%, 2019 US)
