Membrane properties that shape the evolution of membrane enzymes

Local anesthesia is a drug that penetrates the nerve cell membrane and binds to the voltage gate sodium channel, inhibiting the membrane potential and neurotransmission. It is mainly used in clinical uses to address the pain of surgical procedures in the local area. Local anesthetics (LAs), however, can be incorporated into the membrane, reducing the thermal stability of the membrane as well as altering membrane properties such as fluidity, permeability, and lipid packing order. The effects of LAs on the membrane are not yet fully understood, despite a number of previous studies. In particular, it is necessary to analyze which is the more dominant factor, the membrane affinity or the structural perturbation of the membrane. To analyze the effects of LAs on the cell membrane and compare the results with those from model membranes, morphological analysis and 50% inhibitory concentration (IC50) measurement of CCD-1064sk (fibroblast, human skin) membranes were carried out for lidocaine (LDC) and tetracaine (TTC), the most popular LAs in clinical use. Furthermore, the membrane affinity of the LAs was quantitatively analyzed using a colorimetric polydiacetylene assay, where the color shift represents their distribution in the membrane. Further, to confirm the membrane affinity and structural effects of the membranes, we performed an electrophysiological study using a model protein (gramicidin A, gA) and measured the channel lifetime of the model protein on the free-standing lipid bilayer according to the concentration of each LA. Our results show that when LAs interact with cell membranes, membrane affinity is a more dominant factor than steric or conformational effects of the membrane.

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Phenothiazines alter plasma membrane properties and sensitize cancer cells to injury by inhibiting annexin-mediated repair

Journal of Biological Chemistry ◽

10.1016/j.jbc.2021.101012 ◽

2021 ◽

pp. 101012

Author(s):

Anne Sofie Busk Heitmann ◽

Ali Asghar Hakami Zanjani ◽

Martin Berg Klenow ◽

Anna Mularski ◽

Stine Lauritzen Sønder ◽

...

Keyword(s):

Plasma Membrane ◽

Cancer Cells ◽

Membrane Properties

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Quantitative linear dichroism imaging of molecular processes in living cells made simple by open software tools

Communications Biology ◽

10.1038/s42003-021-01694-1 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Alexey Bondar ◽

Olga Rybakova ◽

Josef Melcr ◽

Jan Dohnálek ◽

Petro Khoroshyy ◽

...

Keyword(s):

Biological Systems ◽

Linear Dichroism ◽

Quantitative Information ◽

Living Cells ◽

Software Tools ◽

Model Systems ◽

Membrane Properties ◽

Polarization Microscopy ◽

Molecular Processes ◽

Wide Range

AbstractFluorescence-detected linear dichroism microscopy allows observing various molecular processes in living cells, as well as obtaining quantitative information on orientation of fluorescent molecules associated with cellular features. Such information can provide insights into protein structure, aid in development of genetically encoded probes, and allow determinations of lipid membrane properties. However, quantitating and interpreting linear dichroism in biological systems has been laborious and unreliable. Here we present a set of open source ImageJ-based software tools that allow fast and easy linear dichroism visualization and quantitation, as well as extraction of quantitative information on molecular orientations, even in living systems. The tools were tested on model synthetic lipid vesicles and applied to a variety of biological systems, including observations of conformational changes during G-protein signaling in living cells, using fluorescent proteins. Our results show that our tools and model systems are applicable to a wide range of molecules and polarization-resolved microscopy techniques, and represent a significant step towards making polarization microscopy a mainstream tool of biological imaging.

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The Deformation of an Erythrocyte Under the Radiation Pressure by Optical Stretch

Journal of Biomechanical Engineering ◽

10.1115/1.2354204 ◽

2006 ◽

Vol 128 (6) ◽

pp. 830-836 ◽

Cited By ~ 10

Author(s):

Yong-Ping Liu ◽

Chuan Li ◽

Kuo-Kang Liu ◽

Alvin C. K. Lai

Keyword(s):

Radiation Pressure ◽

Experimental Situation ◽

Numerical Data ◽

Shear Stiffness ◽

Cell Deformation ◽

Membrane Properties ◽

Optimization Approach ◽

Bending Modulus ◽

Average Shear ◽

Good Agreement

In this paper, the mechanical properties of erythrocytes were studied numerically based upon the mechanical model originally developed by Pamplona and Calladine (ASME J. Biomech. Eng., 115, p. 149, 1993) for liposomes. The case under study is the erythrocyte stretched by a pair of laser beams in opposite directions within buffer solutions. The study aims to elucidate the effect of radiation pressure from the optical laser because up to now little is known about its influence on the cell deformation. Following an earlier study by Guck et al. (Phys. Rev. Lett., 84, p. 5451, 2000; Biophys. J., 81, p. 767, 2001), the empirical results of the radiation pressure were introduced and imposed on the cell surface to simulate the real experimental situation. In addition, an algorithm is specially designed to implement the simulation. For better understanding of the radiation pressure on the cell deformation, a large number of simulations were conducted for different properties of cell membrane. Results are first discussed parametrically and then evaluated by comparing with the experimental data reported by Guck et al. An optimization approach through minimizing the errors between experimental and numerical data is used to determine the optimal values of membrane properties. The results showed that an average shear stiffness around 4.611×10-6Nm−1, when the nondimensional ratio of shear modulus to bending modulus ranges from 10 to 300. These values are in a good agreement with those reported in literature.

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