Small, Acid-Soluble Proteins as Biomarkers in Mass Spectrometry Analysis of Bacillu s Spores

Abstract
The use of 1 N HCl for extraction of small, acid-soluble proteins (SASP) from different Bacillus spore species was examined. The extracts were analyzed by high-performance liquid chromatography and matrix-assisted laser desorption mass spectrometry and were found to be both qualitatively and quantitatively superior to extraction by acetonitrile-5% trifluoroacetic acid (70:30, vol/vol). Both major and minor α/β- and γ-type SASP were characterized by their molecular masses or tryptic peptide maps and by searches of both protein and unannotated genome databases. For all but 1 pair ( B. cereus T and B. thuringiensis subsp. Kurstaki ) among the 11 variants studied the suites of SASP masses are distinctive, consistent with the use of these proteins as potential biomarkers for spore identification by mass spectrometry.