Faculty

Education: B.S., Rutgers University (1960); M.S., University of Arizona (1963); PhD., University of Oregon (1969)

Mass Spectrometry Facility Website:
http://mass-spec.science.oregonstate.edu  

Organic & Bioorganic web site:
http://www.chemistry.oregonstate.edu/organic/


Research Interests: Mass Spectrometry

Mass spectrometry lends itself well to solving problems in structural biology. Hydrogen/deuterium (H/D) exchange reactions monitored by electrospray ionization mass spectrometry (ESI-MS) is a particularly powerful tool for studying conformational changes and the folding processes in proteins. Our program has been devoted to elucidating the process of oxidative renaturation of macrophage colony stimulating factor-beta (rhm-CSFß) and determining changes in solvent accessibility in the three-dimensional structure of reduced thioredoxin when alkylated by ethylglutathione and ethylcysteine. The degree of hydrogen isotope exchange in proteins provides useful information on the relative compactness of the their structures. Amide H/D exchange studies on rhM-CSFb shows that in solution the conserved four-helix-bundle of (rhM-CSFb), has fast and moderately fast exchangeable sections of amide hydrogens in the aA helix, and mostly slow exchanging sections of amide hydrogens in the aB, aC, and aD helices. Most of the amide hydrogens in the loop between the b1 and b4 sheets exhibit fast or moderately fast exchange while in the aa 63-67 loop, located at the interface of the two subunits, the exchange was slow. The rates of H/D exchange in rhM-CSF$ appear to correlate well with the exposed surface calculated for each amino acid residue in the crystal structure except for the aD helix where exchange was slower than predicted. Fast hydrogen isotope exchange throughout the segment aa 150-221 in rhM-CSFb indicates that the C-terminal region is unstructured. It is proposed that the anomalous behavior of the aD helix is due to interaction of the C-terminal tail with this helical segment.

Another research area of Dr. Deinzer, is the investigation of fundamental processes of ion formation in resonance electron capture mass spectrometry. The interaction of electrons with electron-capturing molecules producing gas-phase radical anions is a complex process that has received far less attention than the alternative process of producing positive ions. One of the chief barriers to investigating the formation and structure of negative ions has been the lack of techniques with which to form large numbers of them that are sufficiently free of complicating reactions. The trochoidal electron monochromator has been used to generate tunable monoenergetic electrons in the energy range (0-10eV) where electro-active compounds resonantly capture electrons. We have now constructed a new trochoidal electron monochromator time-of-flight mass spectrometer (EM-TOF-MS) that will allow us to produce 3-D spectra in real time, study metastable ion decomposition, and evaluate the effects of temperature on negative ion production. This instrument is the first of its kind.


Representative Publications

  • Conformational changes in chemically modified Escherichia coli thioredoxin monitored by H/D exchange and electrospray ionization mass spectrometry, 2002, Protein Science, 11, 1320.
  • Mass-spectrometric analysis of agonist-induced retinoic acid receptor conformational change, 2002, Biochemical Journal, 362, 173.
  • Hydrogen/deuterium exchange and mass spectrometric analysis of a protein containing multiple disulfide bonds: solution structure of recombinant macrophage colony stimulating factor-beta (rhM-CSFb), 2002, Protein Science, 11, 2113.
  • Conformational Analysis of Intermediates Involved in the in Vitro Folding Pathways of Recombinant Human Macrophage Colony Stimulating Factor b by Sulfhydryl Group Trapping and Hydrogen/Deuterium Pulsed Labeling, 2002, Biochemistry, 41, 15495..