Methods and tools for mass spectrometric lipidome analysis

This thesis consists of four parts. The first part addresses issues related to quantitative analysis of phospholipid compositions of cells and tissues by mass spectrometry. In particular, the effects of phospholipid structure and concentration were investigated. The second part describes a new computational method for calculation of the unit resolution isotopic distribution for any compound, given the isotope abundances of the elements it consists of. In the third part, software (LIMSA) for processing mass spectrometric data from complex lipid samples was developed and tested. The fourth part of the thesis makes use of the tools listed above and a novel mass-spectrometric approach was developed to determine the substrate specificities of three secretory phospholipases in unprecedented detail.