Sigma Xi Postdoctoal Poster Presentation Abstract


Presenter name:            Matthew J. Vergne

Mentor name:               Michael J. Welch

Division:                       839

Laboratory:                  CSTL

Room and Building:       Room A153, Building 227

Mail Stop:                    8392

Telephone:                    3941

FAX:                            301-977-0685


Sigma Xi member:        no



Mass Spectrometry Studies on the Reproducibility of Protein Digestion


Matthew J. Vergne, David M. Bunk, and Michael J. Welch

Analytical Chemistry Division, Chemical Science and Technology Laboratory

National Institute of Standards and Technology, Gaithersburg, MD 20899-8392


            Mass spectrometry quantification of individual proteins from biological samples has the potential to be a more selective and accurate method than immunoassays routinely performed in clinical chemistry.  However, mass spectrometric quantification of intact proteins has proven to be difficult due to structural heterogeneity of macromolecular protein.  A different approach to quantification is to determine the amounts of protein fragments (peptides) produced from trypsin digests with the assumption that the molar amount of each studied peptide is equal the molar amount of the studied protein.  To determine the feasibility of peptide quantification, the reproducibility and completeness of protein digests was tested.

            Bovine serum albumin (BSA) was chosen as a model protein.  Three BSA in-solution trypsin digests were prepared on three different days for a total of nine digests.  Each sample was digested over a 48-hour time period.  The digest solutions were analyzed using capillary LC/MS.  The peak area ratios of peptide pairs with similar elution times in each sample were calculated.  The coefficients of variation (CV) of the area ratios between samples and between days were evaluated along with the precision of the method itself.  The feasibility of quantification of peptides using isotopically labeled internal standards of peptides will be evaluated.