High Resolution MS of Enzymatic Digest Fragments from a Sulfur Mustard and a Phosgene Protein Adduct
EMSL Project ID
1760
Abstract
We are currently investigating two protein-CWA adducts: 1) human serum albumin (HSA)-sulfur mustard (HD), and 2) HSA-phosgene (a CWA). HSA-HD shows random alkylation, as was established by experiments with 35S labelled HD; however, an abundant adduct is formed by reaction with the single free cysteine residue (Cys34). By treating the protein adduct with pronase, a HD-tripeptide is obtained which can selectively and sensitively be detected because it has a single MS/MS fragment (m/z 105, characteristic of HD adducts). This method was recently published,1 but we would like to be able to detect lower quantities. A lower detection limit is probably attainable with a ion trap MS; however, an ion trap is not suitable because the MS/MS fragment at 105 m/z is not easily accessible. A Triple Quadrupole instrument has the MS/MS capability and potentially offers the required gain in sensitivity. HSA-Phg shows two characteristic tryptic peptides. One of the peptides can be used for quantification (a CO-dipeptide) but shows a major interference in the blank. Neither the QTOF nor the LC can be used to separate the two. We would like to know 1) whether the interference is truly isobaric at higher mass resolution 2) if possible, to identify the interference by MS/MS so that it might be used as a means of distinguishing between analyte and interferent. 1) Noort, D.; Hulst, A.G.; De Jong, L.P.A.; Benschop, H.P., Alkylation of Human Serum Albumin by Sulfur Mustard in Vitro and in Vivo: Mass Spectrometric Analysis of a Cysteine Adduct as a Sensitive Biomarker of Exposure, Chem.Res. Toxicol. 12 (1999), 715-721.
Project Details
Project type
Exploratory Research
Start Date
1999-12-02
End Date
2001-10-17
Status
Closed
Released Data Link
Team
Principal Investigator