Dynamics of Model Membranes by NMR

Timoszyk, Anna

doi:10.5772/intechopen.69866

Cited by 3 publications

(2 citation statements)

References 53 publications

(97 reference statements)

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“…These findings indicate that the observed changes can be ascribed to lowering rigidity of phospholipid molecules in the liposomes and show that the presence of the TM molecules in DPPC liposomes lead to its fluidization. The deconvolution of DSC traces indicate the formation of different ordered structures formed from the existing components, which include regions with higher TM concentrations, leading to the formation of cubic or hexagonal mixed micelles formed from DPPC-and TM-enriched molecules [56][57][58][59][60]. Presented results have shown that increasing TM presence embedded into DPPC strongly affect its phase properties in a similar way as observed for temperature-induced phase transitions, thus indicating its possible role in transduction of membrane processes.…”

Section: Discussionsupporting

confidence: 62%

Assessment of DPPC Liposome Disruption by Embedded Tocopheryl Malonate

et al. 2023

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In this study, the effect of α-tocopheryl malonate (TM) on physical and structural properties of DPPC liposomes was investigated using ANS fluorescence, DPH, and TMA–DPH anisotropy fluorescence and differential scanning calorimetry (DSC) methods. The presence of embedded TM in DPPC liposomes caused alteration in its phase transition temperatures, structural order, dynamics, and hydration of head groups increasingly with growing TM concentration. The ANS fluorescence results demonstrated that increasing TM presence in the DPPC gel phase due to interrupted membrane structure caused the formation of new binding sites. Temperature investigations in the range of 20 °C to 60 °C showed that increasing temperature rises ANS fluorescence which reaches local and global maxima at 36 °C and 42 °C, respectively. The rising TM concentration at the phase transition temperature of DPPC led to the lowering of ANS fluorescence, indicating a decreased binding of ANS. Simultaneously, during heating, a roughly 10-nm shift of ANS emission maximum was observed. The results indicated that in the fluid phase, the observed quenching appears as a result of increasing accessibility of water molecules into ANS in this region. The DPH results indicated that in the gel phase presence of TM introduced disorder in the hydrophobic acyl chain region led to its fluidization. The TMA–DPH results indicated an increasing disorder in the interface region and an increasing hydration of head group atoms at the surface of the membrane. The increasing concentration of TM results in the formation of multicomponent DSC traces, suggesting the formation of another structural phase. The applied methods proved that the incorporation of TM into DPPC membrane results in the interaction of malonate moiety with DPPC head group atoms in the interphase layer and induces the interruption in the membrane packing order, leading to its structural changes. The presented results show that TM presence could regulate the membrane properties, thus it may indicate one of the possible mechanisms responsible for the effective disruption of cell membranes by TM. The knowledge of molecular mechanism how TM interacts with the membrane will help to elucidate its possible pharmacological activity.

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Section: Discussionsupporting

confidence: 62%

Assessment of DPPC Liposome Disruption by Embedded Tocopheryl Malonate

et al. 2023

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“…Regardless of the method of preparation, the presence of rhamnolipids contributes to a decrease in CSA

compared to the spectrum of the control sample. A decrease in the values of CSA

with the presence of rhamnolipids means an increase in the rotational mobility of the head group of phospholipids [ 36 , 49 , 50 , 51 , 52 ]. However, the magnitude of this effect depends on the way rhamnolipids are added.…”

Section: Results and Discussionmentioning

confidence: 99%

Effects of Natural Rhamnolipid Mixture on Dioleoylphosphatidylcholine Model Membrane Depending on Method of Preparation and Sterol Content

Potapov

Gordeev²,

Biktasheva³

et al. 2023

Membranes

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Rhamnolipids as biosurfactants have a potentially wide range of applications, for example, as “green” surfactants or components of drug delivery systems, which is associated with the features of their interaction with cell membranes. However, as noted in the literature, those kind of features have not been sufficiently studied now. This paper presents a study of the interaction of a natural mixture of rhamnolipids produced by bacteria of the rhizosphere zone of plants Pseudomonas aeruginosa with model membranes—liposomes based on dioleoylphosphatidylcholine (DOPC), depending on the method of their preparation and the content of sterols—ergosterol, cholesterol, lanosterol. Liposomes with rhamnolipids were prepared by two protocols: with film method from a mixture of DOPC and rhamnolipids; with film method from DOPC and injection of water solution of rhamnolipids. Joint analysis of the data of 31P NMR spectroscopy and ATR-FTIR spectroscopy showed that in the presence of rhamnolipids, the mobility of the head group of the DOPC phospholipid increases, the conformational disorder of the hydrophobic tail increases, and the degree of hydration of the C=O and P=O groups of the phospholipid decreases. It can be assumed that, when prepared from a mixture, rhamnolipids are incorporated into the membrane in the form of clusters and are located closer to the middle of the bilayer; while when prepared by injection, rhamnolipid molecules migrate into the membrane in the form of individual molecules and are located closer to the head part of phospholipids. The sterol composition of the model membrane also affects the interaction of rhamnolipids with the membrane. Here it is worth noting the possible presence of type of interaction between rhamnolipids and ergosterol differ from other investigated sterols, due to which rhamnolipid molecules are embedded in the area where ergosterol is located.

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