Conformational changes of membrane proteins are accompanied by deformation in the surrounding lipid bilayer. To gain insight into the energetics of membrane deformation, the phase behavior of dimyristoylphosphatidylcholine (DMPC) membranes in the presence of the dipole potential, ψ, modifiers was investigated by differential scanning calorimetry. 7-Ketocholesterol, which weakens ψ and reduces membrane-perpendicular dipole-dipole repulsion, causes a discrete second peak on the high-temperature side of the main transition, whereas 6-ketocholestanol, which strengthens ψ and increases membrane-perpendicular dipole-dipole repulsion, merely produces a shoulder. Measurements on pure DMPC vesicles showed that the observed temperature profile could not be explained by a single endothermic process, that is, breaking of van der Waals forces between hydrocarbon chains alone. Removal of NaCl from the buffer caused an increase in the main transition temperature and the appearance of an obvious shoulder, implicating polar interactions. Consideration of the phosphatidylcholine (PC) head group dipole moment indicates direct interactions between PC dipoles that are unlikely to account for the additional process. It seems more likely that the breaking of an in-plane hydrogen-bonded network consisting of hydrating water dipoles together with zwitterionic lipid head groups is responsible. The evidence presented supports the idea that the breaking of van der Waals forces between lipid tails required for the main phase transition of PC membranes is coupled to partial breaking of a hydrogen-bonded network at the membrane surface.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648055PMC
http://dx.doi.org/10.1021/acsomega.8b03102DOI Listing

Publication Analysis

Top Keywords

polar interactions
8
main phase
8
phase transition
8
membrane-perpendicular dipole-dipole
8
dipole-dipole repulsion
8
main transition
8
process breaking
8
breaking van
8
van der
8
der waals
8

Similar Publications

New tributyltin(IV) complexes containing the carboxylate ligands 3-(4-methyl-2-oxoquinolin-1(2H)-yl)propanoic acid () and 2-(4-methyl-2-oxoquinolin-1(2H)-yl)acetic acid () have been synthesized. Their structures have been determined by elemental microanalysis, FT-IR and multinuclear NMR (H, C and Sn) spectroscopy and X-ray diffraction study. A solution state NMR analysis reveals a four-coordinated tributyltin(IV) complex in non-polar solvents, while an X-Ray crystallographic analysis confirms a five-coordinated trigonal-bipyramidal geometry around the tin atom due to the formation of 1D chains.

View Article and Find Full Text PDF

This article reports on the scalability of a combined wet grinding technique applying planetary ball mill and ZrO pearls as the grinding medium. After the determination of the parameters in a laboratory scale, the tenfold scale-up method was set. Meloxicam (MEL) was used as a nonsteroidal anti-inflammatory drug (NSAID) intended for per os delivery.

View Article and Find Full Text PDF

In order to investigate the mechanism of mechanical performance enhancement and the curing mechanisms of acrylate emulsion (AE) in cement and magnesium slag (MS) composite-stabilized soil (AE-C-M), this study has conducted a comprehensive analysis of the compressive strength and microstructural characteristics of AE-C-M stabilized soil. The results show that the addition of AE significantly improves the compressive strength of the stabilized soil. When the AE content is 0.

View Article and Find Full Text PDF

Novel Nuclease MbovP701 with a Yqaj Domain Is Interrelated with the Growth of .

Microorganisms

December 2024

National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.

() is characterized by a reduced genomic size and limited synthetic capacity, including the inability to synthesize nucleotides de novo, relies on nucleases for nutrient acquisition and survival. A number of nucleases have been implicated in pathogenicity, facilitating substrate degradation and contributing to DNA repair mechanisms that enhance bacterial persistence. The present study confirmed that the T5.

View Article and Find Full Text PDF

A Review of Cascaded Metasurfaces for Advanced Integrated Devices.

Micromachines (Basel)

December 2024

State Key Laboratory of Precision Measuring Technology & Instruments, Tianjin University, Tianjin 300072, China.

This paper reviews the field of cascaded metasurfaces, which are advanced optical devices formed by stacking or serially arranging multiple metasurface layers. These structures leverage near-field and far-field electromagnetic (EM) coupling mechanisms to enhance functionalities beyond single-layer metasurfaces. This review comprehensively discusses the physical principles, design methodologies, and applications of cascaded metasurfaces, focusing on both static and dynamic configurations.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!