cerevisiae and S. bayanus is similar, showing always four major GP species with 32 and 34 carbon atoms and one to two double bonds, except for the class of CA, which possesses a broader distribution due to its variation possibilities based on four bound fatty acids. It has to be noted that in the classes of PE and PC the most abundant species GP(34:2) of S. cerevisiae is the second most abundant species of S. bayanus, and vice versa for the species GP(32:2). Concerning the minor components, the lipid profiles

of both yeast strains also show remarkable analogies. Only few Inhibitors,research,lifescience,medical species with 36 carbon atoms in the acyl chains could be identified and also some odd numbered species, bearing 31 and 33 carbon atoms. The maximum number of double bonds for a GP-species was two, except for CAs, where minor species with up to seven double bonds Inhibitors,research,lifescience,medical were identified.

As PGs only were identified for S. bayanus, the diagram is not shown. The main species identified were PG(32:1), 40.8% ± 1.6% and PG(34:1), 43.1% ± 2.2%. Furthermore, PG(28:0), PG(26:0) and PG(32:2), contributing 7.7% ± 0.9%, 5.6% ± 0.8% and 2.8% ± 0.9% were identified. The GP profiling data obtained for S. cerevisiae within this work are in large parts in good agreement with previously published data by Ejsing et al. [11], who used a quantitative shotgun mass spectrometric approach. In both studies the same major GP species Inhibitors,research,lifescience,medical were identified, in particular PE(32:1), PE(32:2), PE(34:1), PE(34:2), PC(32:1), PC(32:2),

PC(34:1), PC(34:2), PI(28:0), PI(32:1), PI(32:2), PI(34:1), PI(34:2), PS(32:1), PS(32:2), PS(34:1), and PS(34:2). Different results, referring to the study Inhibitors,research,lifescience,medical of Ejsing et al. were for example obtained for the class of CAs. The major species identified in this study were CA(66:3), CA(66:4), CA(68:3), CA(68:4) and CA(70:4), whereas Ejsing et al. found the species CA(64:4), Inhibitors,research,lifescience,medical CA(66:2) beside CA(66:4) and CA(68:4). In addition, no phosphatidic acid (PA) could be detected in S. cerevisiae in contrast to the findings of Ejsing et al., and each positive Profiler-Merger-Viewer software hit turned out to be an in-source fragmentation artifact isothipendyl of the corresponding PS species. However, the fact that PAs could be unambiguously identified in the other yeast strains, demonstrates that this class can also be detected by the applied method (see Table S1 of the Supporting Information), but PAs may be below the limits of detection in the case of S. cerevisiae. In addition to these predominant GP classes, in both studies minor amounts of PG could be identified, as well as the lyso-forms of PE, PC, and PI. Moreover, the intermediates of PC biosynthesis via the PE-methylation pathway were identified, i.e. MMPE and DMPE. These Epigenetics Compound Library chemical structure results are also confirmed by other studies, where FA(16:1), FA(16:0) and FA(18:1) are described as most abundant fatty acids linked to the GPs. However, also FA(18:0) and FA(14:0) were frequently reported, which is in good accordance with the study of Ejsing et al.