and Mass Spectrometry

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An Integrated Mass Spectrometry Method for Protein Analysis: Desorption/Ionization on Silicon (DIOS)

presented by

John J. Thomas
The Scripps Research Institute

November 30, 2000

The Scripps Research Institute, W.M. Keck Foundation Amphitheater


John received his B.S. in Chemistry from the Univ. of Pittsburgh and worked in separations technologies and environmental fields before heading to graduate school at Villanova. There John earned an M.S. in Analytical Chemistry and went on to earn his Ph.D. in the same field from the University of Maryland. Under the advisement of Catherine Fenselau, John's thesis research focused on the "Mass Spectrometric Characterization of Viral Proteins." John is currently conducting post-doctoral research in Gary Siuzdak's lab at The Scripps Research Institute where, among other projects, he is developing a new, matrix-free desorption/ ionization technique.


Desorption/ ionization on silicon (DIOS) is a new laser desorption technique that circumvents limitations of traditional MALDI analysis by eliminating the need for a matrix.Here we demonstrate the potential of DIOS-MS for complete protein analysis, including functional characterization, inhibition, and identification. Functional assays were performed on an esterase, a lipase, a glucosidase, and exo- and endo- proteases. In the absence of matrix, the same protein sample can be digested, and identified using the peptide masses and protein database searching. Desorption/ionization on porous silicon (DIOS), a new matrix-free method of generating gas phase ions, demonstrates the potential to manipulate, analyze, and characterize proteins directly on one chip.

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