Date of Award
Kinsel, Gary R.; Kinsel, Mary
Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has emerged in recent years as one of the most powerful tools available for characterizing the molecules involved in the biochemistry of life. Metal oxide laser ionization (MOLI) is a recently described variation on MALDI in which a metal oxide, rather than an organic acid, is utilized as the matrix. Unlike other metal oxides, Cerium(IV) Oxide (CeO2) demonstrates a unique property of laser induced catalytic side chain cleavage of fatty acids when applied to phospholipids and energized by standard lasers found in MALDI-TOF-MS instruments.
In previous work, a technique for CeO2 deposition on mouse brain tissue was developed that allows fatty acyl catalysis directly from tissue for possible bacterial identification. Although MOLI using CeO2 was shown to be promising for this application, the mechanism of fatty acyl catalysis remains poorly understood. In the current studies, a negative ion mode calibration mixture is first optimized to ensure mass-to-charge (m/z) assignments are accurate thereby allowing structural assignments to be confirmed. This calibrant mixture is then used in the analysis of a phospholipid standard used in previous work; palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC). This work ensures that the mouse brain imaging results obtained earlier can be replicated on the Bruker MicroFlex MALDI-TOF-MS. With this assurance, structural variants of POPC are studied to determine how slight variations in structure affect the catalytic cleavage with a goal to gain insight into the cleavage mechanism. Additionally, computational studies are performed to gain insight into the structural and electronic properties of phospholipids and their derivatives.