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Mechanism of Ionization in Matrix-Assisted Laser Desorption Ionization (MALDI):

Ajax Group. Joshua P. Layfield Jordan C. Vincent Desiree M. Bates Ashley K. Tucker Sara E. Ray Ron C. Estler. Mechanism of Ionization in Matrix-Assisted Laser Desorption Ionization (MALDI): How does proton transfer occur. http://pslc.ws/mactest/maldi.htm. MALDI Overview.

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Mechanism of Ionization in Matrix-Assisted Laser Desorption Ionization (MALDI):

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  1. Ajax Group Joshua P. Layfield Jordan C. Vincent Desiree M. Bates Ashley K. Tucker Sara E. Ray Ron C. Estler Mechanism of Ionization in Matrix-Assisted Laser Desorption Ionization (MALDI): How does proton transfer occur http://pslc.ws/mactest/maldi.htm

  2. MALDI Overview • MALDI is a soft ionization technique that has revolutionized high-molecular weight mass spectrometry • Technique used to measure the molecular weights of a number of systems • Proteins • Polysaccharides • Glyco-lipids • Synthetic Polymers • Nobel Prize Awarded to Fenn and Tanaka in 2002 for the development of soft ionization techniques http://www.magnet.fsu.edu/education /tutorials/tools/ionization_maldi.html

  3. Advantages Used for Disease Diagnosis Able to Ionize Large molecules Accurate / Rapid Analysis Fast Technique Disadvantages Lack of Reproducibility Sample Hot Spots Lack of proper Matrix Molecules Poor Fundamental Understanding of the Mechanism Lack of Rational Design MALDI Overview

  4. Proposed Mechanisms • Cluster Ionization • Ionization occurs after desorption from the matrix • Proton transfer occurs in the gas-phase or in small matrix clusters

  5. Proposed Mechanisms • Photoionzation • Multiple matrix molecule photon absorption • Energy transferred to the analyte in the solid-phase or the gas-phase

  6. Run a MD canonical simulation (CHARMM) to determine the general structure of the matrix protein interactions Optimize the structures of potentially relevant matrix/analyte conformations using electronic structure theory Study the energetics of the proton transfer reactions using intrinsic-reaction-coordinate electronic structure studies for a test set of amino acid/benzoic acid derivatives Methods

  7. Methods

  8. Future Challenges • Move beyond pure molecular mechanics • Investigate other possibilities for matrix molecules • Move beyond the gas phase for the MD simulations • Testing new matrix molecules for predictive recommendations to experimentalists

  9. Special Thanks…

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