Effect of γ-Oryzanol on the LE-LC Phase Coexistence Region of DPPC Langmuir Monolayer.

IF 2.3 4区 生物学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY
Journal of Membrane Biology Pub Date : 2023-12-01 Epub Date: 2023-06-03 DOI:10.1007/s00232-023-00288-8
Raghavendra, Bharat Kumar, Siva N Chari
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Abstract

We have studied the effect of relative composition of γ-Oryzanol (γ-Or) on the liquid expanded-liquid condensed phase coexistence region in the mixed Langmuir monolayer of γ-Or and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) molecules at air-water interface. The surface manometry studies at a fixed temperature show that the mixture of γ-Or and DPPC forms a stable monolayer at air-water interface. As the relative composition of γ-Or increases the range of area per molecule over which the coexistence of liquid expanded (LE)-liquid condensed (LC) phases exists reduces. Although the LE-LC phase coexistence corresponds to the first-order phase transition, the slope of the surface pressure-area per molecule isotherm is non-zero. Earlier studies have attributed the non-zero slope in LE-LC phase coexistence region to the influence of the strain between the ordered LC phase and disordered LE phase. The effect of strain on the coexistence of LE-LC phases can be studied in terms of molecular density-strain coupling. Our analysis of the liquid condensed-liquid expanded coexistence region in the isotherms of mixed monolayers of DPPC and γ-Or shows that with the increase in the mole fraction of sterol in the mixed monolayer the molecular lateral density-strain coupling increases. However, at 0.6 mole fraction of γ-Or in the mixed monolayer the coupling decreases. This is corroborated by the observation of minimum Gibb's free energy of the mixed monolayer at this relative composition of γ-Or indicating better packing of molecules.

Abstract Image

γ-谷维醇对DPPC Langmuir单层LE-LC相共存区的影响
本文研究了γ-谷米醇(γ-Or)的相对组成对γ-Or和1,2-双棕榈酰- n-甘油-3-磷酸胆碱(DPPC)分子在空气-水界面混合Langmuir单层中液胀-液凝聚共存区的影响。在固定温度下的表面测压研究表明,γ-Or和DPPC的混合物在空气-水界面形成稳定的单层。随着γ-Or相对组成的增加,液相膨胀相(LE)-液相凝聚相(LC)共存的分子面积范围减小。虽然l - lc相共存对应于一阶相变,但每分子等温线的表面压力-面积斜率不为零。早期的研究将LE-LC相共存区的非零斜率归因于有序LC相和无序LE相之间应变的影响。应变对LE-LC相共存的影响可以从分子密度-应变耦合的角度来研究。对DPPC和γ-Or混合单分子膜等温线上的液凝-液胀共存区分析表明,随着混合单分子膜中甾醇摩尔分数的增加,分子侧密度-应变耦合增大。然而,当混合单层中γ-Or的摩尔分数为0.6时,耦合减弱。在γ-Or的相对组成下,观察到混合单层的最小吉布自由能证实了这一点,表明分子的填充更好。
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来源期刊
Journal of Membrane Biology
Journal of Membrane Biology 生物-生化与分子生物学
CiteScore
4.80
自引率
4.20%
发文量
63
审稿时长
6-12 weeks
期刊介绍: The Journal of Membrane Biology is dedicated to publishing high-quality science related to membrane biology, biochemistry and biophysics. In particular, we welcome work that uses modern experimental or computational methods including but not limited to those with microscopy, diffraction, NMR, computer simulations, or biochemistry aimed at membrane associated or membrane embedded proteins or model membrane systems. These methods might be applied to study topics like membrane protein structure and function, membrane mediated or controlled signaling mechanisms, cell-cell communication via gap junctions, the behavior of proteins and lipids based on monolayer or bilayer systems, or genetic and regulatory mechanisms controlling membrane function. Research articles, short communications and reviews are all welcome. We also encourage authors to consider publishing ''negative'' results where experiments or simulations were well performed, but resulted in unusual or unexpected outcomes without obvious explanations. While we welcome connections to clinical studies, submissions that are primarily clinical in nature or that fail to make connections to the basic science issues of membrane structure, chemistry and function, are not appropriate for the journal. In a similar way, studies that are primarily descriptive and narratives of assays in a clinical or population study are best published in other journals. If you are not certain, it is entirely appropriate to write to us to inquire if your study is a good fit for the journal.
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