20.500.12556/RUL-173408 Prehod porotvornega sredstva skozi fosfolipidno membrano Passage of the pore-forming agent through phospholipid membrane Ciljno delovanje in toksičnost porotvornih antibiotikov, kot je nistatin, sta neposredno povezana z njihovo sposobnostjo prehajanja skozi fosfolipidne membrane. Da bi raziskali, ali in na kakšen način ta sredstva prehajajo skozi fosfolipidno membrano, smo razvili eksperimentalno metodo, ki temelji na merjenju časa od prenosa velikanskih unilamelarnih vesiklov (GUV) in multivesikularnih vesiklov (MVV) v raztopino porotvornega sredstva do njihovega poka. MVV-ji so sestavljeni iz notranjega (inGUV) in zunanjega (outGUV) vesikla, pri čemer čas poka vsakega določimo ločeno. Do pokov vesiklov pride zaradi hitre in številčne tvorbe por v membrani, kar je mogoče le pri visokih koncentracijah porotvornega sredstva. Vesikle smo opazovali s faznokontrastno mikroskopijo. Merilo, ki pove, ali sredstvo lahko preide skozi membrano ali ne, je razlika v času, ki ga inGUV preživi v raztopini po poku outGUV-a, v primerjavi s časom poka GUV-a enake velikosti. Če je ta čas krajši, to kaže, da je inGUV prišel v stik s porotvornim sredstvom že pred pokom outGUV-a, kar pomeni, da sredstvo prehaja skozi membrano. Na podlagi izmerjenih časov pokov smo lahko ocenili tudi spodnjo mejo membranske prepustnosti za dano porotvorno sredstvo. Z razvito metodo smo pokazali, da porotvorno sredstvo nistatin lahko prehaja skozi membrano iz POPC, ki vsebuje ergosterol (15 ali 45 mol\%), kadar je ta izpostavljena raztopini z visoko koncentracijo nistatina (250 ali 500 $\mu$M). V teh pogojih namreč pride do pokov vesiklov. Na podlagi rezultatov smo predlagali mehanizem prehoda nistatina, po katerem je prehod mogoč le, kadar nistatin v membrani tvori transmembransko poro. The targeted activity and toxicity of pore-forming antibiotics such as nystatin are directly linked to their ability to cross phospholipid membranes. To investigate whether such agents can pass through the lipid bilayer and to what extent, we developed an experimental method based on measuring the time between the transfer of giant unilamellar vesicles (GUVs) and multivesicular vesicles (MVVs) into a solution of the pore-forming agent and the time of their rupture. MVVs are composed of an inner (inGUV) and an outer (outGUV) vesicle, and the rupture time of each is recorded separately. Vesicle rupture occurs due to rapid and extensive pore formation in the membrane, which happens only at high concentrations of the pore-forming agent. Vesicles were observed using phase-contrast microscopy. The key indicator of membrane permeability is the difference between the time that inGUV remains intact after the rupture of the outGUV and the rupture time of control GUV of the same size. If the inGUV ruptures sooner, this indicates that it came into contact with the pore-forming agent before the outGUV ruptured, implying that the agent permeated the membrane of the outGUV. Based on the measured rupture times the lower limit of membrane permeability for a given agent could also be estimated. Using this method, we demonstrated that the pore-forming agent nystatin can pass through a POPC membrane containing ergosterol (15 or 45 mol\%) when exposed to high nystatin concentrations (250 or 500~$\mu$M). Under these conditions, vesicle rupture occurs due to pore formation in the membrane. Based on our results, we proposed a mechanism in which nystatin passes through the membrane only when it forms a transmembrane pore. fosfolipidni dvosloj porotvorno sredstvo transmembranska pora nistatin phospholipid bilayer pore-forming agent transmembrane pore nystatin true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2025-09-17 08:15:24 2025-09-17 08:15:27 2025-11-08 04:01:45 0000-00-00 00:00:00 2025 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 153725 249621251 19552.pdf 19552.pdf 1 D10E1FF4F8CEF927EEAB2E6B80444B92 5aa343468ed5962b6a6f9bed7cdb56267ecafb90aaea2f060ef0a9aacd5d8f2a 89cd0736-938d-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=217818 Fakulteta za matematiko in fiziko 0 0 0