@article {2019|2081,
	title = {Visualizing Biological Membrane Organization and Dynamics.},
	journal = {J Mol Biol},
	volume = {431},
	year = {2019},
	month = {2019 05 03},
	pages = {1889-1919},
	abstract = {<p>Biological membranes are fascinating. Santiago Ram{\'o}n y Cajal, who received the Nobel prize in 1906 together with Camillo Golgi for their work on the nervous system, wrote \&quot;[\&hellip;]in the study of this membrane[\&hellip;] I felt more profoundly than in any other subject of study the shuddering sensation of the unfathomable mystery of life\&quot;. The visualization and conceptualization of these biological objects have profoundly shaped many aspects of modern biology, drawing inspiration from experiments, computer simulations, and the imagination of scientists and artists. The aim of this review is to provide a fresh look on current ideas of biological membrane organization and dynamics by discussing selected examples across fields.</p>
},
	keywords = {Animals, Cell Membrane, Humans, Lipid Bilayers, Microscopy, Atomic Force, Microscopy, Electron, Transmission, Molecular Dynamics Simulation},
	issn = {1089-8638},
	doi = {10.1016/j.jmb.2019.02.018},
	author = {Marc Baaden}
}
@article {2014|1669,
	title = {CHARMM36 united atom chain model for lipids and surfactants.},
	journal = {J. Phys. Chem. B},
	volume = {118},
	number = {2},
	year = {2014},
	month = {jan},
	pages = {547{\textendash}556},
	publisher = {, Maryland 20742, United States.},
	abstract = {Molecular simulations of lipids and surfactants require accurate parameters to reproduce and predict experimental properties. Previously, a united atom (UA) chain model was developed for the CHARMM27/27r lipids (H{\'e}nin, J., et al. J. Phys. Chem. B. 2008, 112, 7008-7015) but suffers from the flaw that bilayer simulations using the model require an imposed surface area ensemble, which limits its use to pure bilayer systems. A UA-chain model has been developed based on the CHARMM36 (C36) all-atom lipid parameters, termed C36-UA, and agreed well with bulk, lipid membrane, and micelle formation of a surfactant. Molecular dynamics (MD) simulations of alkanes (heptane and pentadecane) were used to test the validity of C36-UA on density, heat of vaporization, and liquid self-diffusion constants. Then, simulations using C36-UA resulted in accurate properties (surface area per lipid, X-ray and neutron form factors, and chain order parameters) of various saturated- and unsaturated-chain bilayers. When mixed with the all-atom cholesterol model and tested with a series of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/cholesterol mixtures, the C36-UA model performed well. Simulations of self-assembly of a surfactant (dodecylphosphocholine, DPC) using C36-UA suggest an aggregation number of 53 {\textpm} 11 DPC molecules at 0.45 M of DPC, which agrees well with experimental estimates. Therefore, the C36-UA force field offers a useful alternative to the all-atom C36 lipid force field by requiring less computational cost while still maintaining the same level of accuracy, which may prove useful for large systems with proteins.},
	keywords = {analogs /\&/ derivatives/chemistry, chemistry, Cholesterol, Dimyristoylphosphatidylcholine, Lipid Bilayers, Lipids, Micelles, Molecular Dynamics Simulation, Phosphorylcholine, Surface-Active Agents},
	doi = {10.1021/jp410344g},
	author = {Lee, Sarah and Tran, Alan and Allsopp, Matthew and Lim, Joseph B. and J{\'e}r{\^o}me H{\'e}nin and Klauda, Jeffery B.}
}
@article {2014|1717,
	title = {Lipid concentration and molar ratio boundaries for the use of isotropic bicelles.},
	journal = {Langmuir},
	volume = {30},
	number = {21},
	year = {2014},
	month = {jun},
	pages = {6162{\textendash}6170},
	publisher = {Department of Chemistry, Universit{\'e} du Qu{\'e}bec {\`a} Montr{\'e}al and Centre Qu{\'e}b{\'e}cois sur les Mat{\'e}riaux Fonctionnels , P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8.},
	abstract = {Bicelles are model membranes generally made of long-chain dimyristoylphosphatidylcholine (DMPC) and short-chain dihexanoyl-PC (DHPC). They are extensively used in the study of membrane interactions and structure determination of membrane-associated peptides, since their composition and morphology mimic the widespread PC-rich natural eukaryotic membranes. At low DMPC/DHPC (q) molar ratios, fast-tumbling bicelles are formed in which the DMPC bilayer is stabilized by DHPC molecules in the high-curvature rim region. Experimental constraints imposed by techniques such as circular dichroism, dynamic light scattering, or microscopy may require the use of bicelles at high dilutions. Studies have shown that such conditions induce the formation of small aggregates and alter the lipid-to-detergent ratio of the bicelle assemblies. The objectives of this work were to determine the exact composition of those DMPC/DHPC isotropic bicelles and study the lipid miscibility. This was done using (31)P nuclear magnetic resonance (NMR) and exploring a wide range of lipid concentrations (2-400 mM) and q ratios (0.15-2). Our data demonstrate how dilution modifies the actual DMPC/DHPC molar ratio in the bicelles. Care must be taken for samples with a total lipid concentration <=250 mM and especially at q \~{} 1.5-2, since moderate dilutions could lead to the formation of large and slow-tumbling lipid structures that could hinder the use of solution NMR methods, circular dichroism or dynamic light scattering studies. Our results, supported by infrared spectroscopy and molecular dynamics simulations, also show that phospholipids in bicelles are largely segregated only when q > 1. Boundaries are presented within which control of the bicelles{\textquoteright} q ratio is possible. This work, thus, intends to guide the choice of q ratio and total phospholipid concentration when using isotropic bicelles.},
	keywords = {chemistry, Circular Dichroism, Detergents, Dimyristoylphosphatidylcholine, Fourier Transform Infrared, Light, Lipid Bilayers, Magnetic Resonance Spectroscopy, Materials Testing, Micelles, Molecular Dynamics Simulation, Phospholipid Ethers, Phospholipids, Radiation, Scattering, Solutions, Spectroscopy, Temperature},
	doi = {10.1021/la5004353},
	author = {Beaugrand, Ma\"{\i}wenn and Arnold, Alexandre A. and J{\'e}r{\^o}me H{\'e}nin and Warschawski, Dror E. and Williamson, Philip T F. and Marcotte, Isabelle}
}
@article {2009|1864,
	title = {Models for phosphatidylglycerol lipids put to a structural test},
	journal = {J. Phys. Chem. B},
	volume = {113},
	number = {19},
	year = {2009},
	pages = {6958{\textendash}6963},
	publisher = {Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA. jhenin@cmm.chem.upenn.edu},
	abstract = {Three atomistic empirical models for phosphatidylglycerol (PG) lipids are tested against structural data in the crystal and liquid crystal states. Simulations of the anhydrous crystal of dimyristoyl-phosphatidylglycerol (DMPG) show that only the CHARMM force field describes the conformation and interactions of PG head groups accurately. The other two models do not reproduce the native network of hydrogen bonds, suggesting the presence of biases in their conformational and nonbonded interaction properties. The CHARMM model is further validated in the biologically relevant liquid crystal phase by comparing experimental small-angle X-ray scattering spectra from DMPG unilamellar vesicles with data calculated from fluid bilayer simulations. The good agreement found in this model-free comparison implies that liquid crystal PG bilayers as described by CHARMM exhibit realistic bilayer thickness and lateral packing. Last, this model is used to simulate a fluid bilayer of palmitoyl-oleoyl-phosphatidylglycerol (POPG). The resulting view of the POPG bilayer structure is at variance with that proposed previously based on simulations, in particular, with respect to lateral packing of head groups and the role of counterions.},
	keywords = {chemistry, Crystallography, Lipid Bilayers, Models, Molecular, Phosphatidylglycerols, Scattering, Small Angle, Water, X-Ray},
	doi = {10.1021/jp900645z},
	author = {J{\'e}r{\^o}me H{\'e}nin and Wataru Shinoda and Michael L Klein}
}
