Characterization of sulfur mustard induced structural modifications in human hemoglobin by liquid chromatography--tandem mass spectrometry.

In this paper we describe the use of tandem mass spectrometry to identify modified sites in human hemoglobin after in vitro exposure to bis(2-chloroethyl) sulfide (sulfur mustard). Globin isolated from human whole blood which had been exposed to sulfur mustard was degraded with trypsin, and the digests were analyzed by micro LC/MS. Alkylated tryptic fragments (alpha-T1, alpha-T4, alpha-T6, alpha-T9, beta-T1, beta-T9, beta-T10, beta-T11, and beta-T10-S-S-beta-T12) could be tentatively assigned upon comparison with a digest from nonexposed globin. Subsequent tandem mass spectrometry of these peptides allowed unambiguous assignment of 5 specific modified residues: alpha-Val-1, alpha-His-20, beta-Val-1, beta-His-77, and beta-His-97. The results demonstrate the usefulness of microbore LC in combination with tandem mass spectrometry for the structural determination of chemically modified peptides and proteins.