Characterization of Botulinum Progenitor Toxins by Mass Spectrometry
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD DIV OF TOXINOLOGY AND AEROBIOLOGY
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Botulinum toxin analysis has renewed importance. This study included the use of nanochromatography-nanoelectrospray-mass spectrometrymass spectrometry to characterize the protein composition of botulinum progenitor toxins and to assign botulinum progenitor toxins to their proper serotype and strain by using currently available sequence information. Clostridium botulinum progenitor toxins from strains Hall, Okra, Stockholm, MDPH, Alaska, Langeland, and 89 representing serotypes A through G, respectively, were reduced, alkylated, digested with trypsin, and identified by matching processed product ion spectra of the tryptic peptides to proteins in accessible databases. All proteins known to be present in progenitor toxins from each serotype were identified. Additional proteins, including flagellins, ORF-X1, and neurotoxin binding protein, not previously reported to be associated with progenitor toxins, were present also in samples from several serotypes. Protein identification was used to assign toxins to a serotype and strain. Serotype assignments were accurate, and strain assignments were best when either sufficient nucleotide or amino acid sequence data were available. Minor difficulties were encountered using neurotoxin-associated protein identification for assigning serotype and strain. This study found that combined nanoscale chromatographic and mass spectrometric techniques can characterize C. botulinum progenitor toxin protein composition and that serotypestrain assignments based upon these proteins can provide accurate serotype and, in most instances, strain assignments using currently available information. Assignment accuracy will continue to improve as more nucleotideamino acid sequence information becomes available for different botulinum strains.