Chemische Sonden zur Aufklärung der Chinoxalindion

α-Hämolysin Wechselwirkung und zur Target-Identifizierung von Salinilactonen

authored by: Karoline Jerye
supervised by: Mark Brönstrup
Abstract: Chemoproteomics has proven to be an effective strategy for elucidating the mode of action of drugs.[1] In this thesis, two chemoproteomic approaches were pursued for two different projects. The first one aimed of identifying the binding site of quinoxalinediones at the target protein α-hemolysin. The affinity-based probe 43 synthesized for this purpose, with a high inhibiting activity on α-hemolysin, was used in photolabeling experiments. MS/MS-experiments identified the amino acids W286 and Y54 as binding sites. The former is in spatial proximity to the region of the protein, which is responsible for recognizing the host cell membrane. Binding of quinoxalinediones in this region could lead to the inactivation of α-hemolysin. Such a mode of action is a variant of so-called pathoblocker approaches and a promising method for rendering antibiotic-resistant Staphylococcus aureus strains harmless. In the second project, the activity-based protein profiling was applied to identify a human target protein of marine natural products named salinilactones. Using a synthesized biotin-salinilactone-conjugate, the family of protein disulfide-isomerases (PDIs) was identified as a target. Inhibiting these enzymes is considered a potential strategy for treating cancer. Synthesis and separation of diastereomers (de > 99%) yielded both salinilactone B enantiomers. With the help of an insulin reduction assay the inhibiting effect of the natural product on the enzyme activity of PDIA1 was demonstrated. Surprisingly, a stronger effect was detected for the (1S,5R)-enantiomer 123, which is less abundant in nature. MS/MS-based studies identified cysteines C53 and C397 of the two catalytic sites of PDIA1 as covalent binding sites of salinilactones. Afterwards, the synthesis of a BODIPY-salinilactone-conjugate enabled the localization in the endoplasmic reticulum in A549 cells by fluorescence microscopy. In this thesis, two mechanisms of interesting synthetic and natural molecules were successfully elucidated.
Organisation(s): Centre of Biomolecular Drug Research (BMWZ)
Type: Doctoral thesis
No. of pages: 452
Publication date: 26.09.2024
Publication status: Published
Sustainable Development Goals: SDG 3 - Good Health and Well-being, SDG 14 - Life Below Water
Electronic version(s): https://doi.org/10.15488/17988 (Access: Open)