Computational studies of plasma lipoprotein lipids

The structure, self-assembly and dynamics of lipid nanodiscs revealed by computational approaches

Nanodisc technology is increasingly being used in structural, biochemical and biophysical studies of membrane proteins. The computational approaches have revealed many important features of nanodisc assembly, structures and dynamics. Therefore, we reviewed the application of computational approaches, especially molecular modeling and molecular dyncamics (MD) simulations, to characterize nanodiscs, including the structural models, assembly and disassembly, protocols for modeling, structural properties and dynamics, and protein-lipid interactions in nanodiscs. More amazing computational studies about nanodiscs are looked forward to in the future.

Targeting structural flexibility in low density lipoprotein by integrating cryo-electron microscopy and high-speed atomic force microscopy

Low-density lipoprotein (LDL) plays a crucial role in cholesterol metabolism. Responsible for cholesterol transport from the liver to the organs, LDL accumulation in the arteries is a primary cause of cardiovascular diseases, such as atherosclerosis. This work focuses on the fundamental question of the LDL molecular structure, as well as the topology and molecular motions of apolipoprotein B-100 (apo B-100), which is addressed by single-particle cryo-electron microscopy (cryo-EM) and high-speed atomic force microscopy (HS-AFM). Our results suggest a revised model of the LDL core organization with respect to the cholesterol ester (CE) arrangement. In addition, a high-density region close to the flattened poles could be identified, likely enriched in free cholesterol. The most remarkable new details are two protrusions on the LDL surface, attributed to the protein apo B-100. HS-AFM adds the dimension of time and reveals for the first time a highly dynamic direct description of LDL, where we could follow large domain fluctuations of the protrusions in real time. To tackle the inherent flexibility and heterogeneity of LDL, the cryo-EM maps are further assessed by 3D variability analysis. Our study gives a detailed explanation how to approach the intrinsic flexibility of a complex system comprising lipids and protein.

HDL and LDL have distinct, opposing effects on LPS-induced brain inflammation

Endotoxemia and sepsis induce neuroinflammation and increase the risk of neurodegenerative disorders although the mechanism by which peripheral infection leads to brain inflammation is not well understood. While circulating serum lipoproteins are known immunometabolites with the potential to modulate the acute phase response and cross the blood brain barrier, their contribution to neuroinflammation during systemic infection is unknown. The objective of this study was to elucidate the mechanisms by which lipoprotein subclasses modulate lipopolysaccharide (LPS)-induced neuroinflammation. Adult C57BL/6 mice were divided into 6 treatment groups, including a sterile saline vehicle control group (n = 9), an LPS group (n = 11), a premixed LPS + HDL group (n = 6), a premixed LPS + LDL group (n = 5), a HDL only group (n = 6) and an LDL only group (n = 3). In all cases injections were administered intraperitoneally. LPS was administered at 0.5 mg/kg, and lipoproteins were administered at 20 mg/kg. Behavioural testing and tissue collection was performed 6 h post-injection. The magnitude of peripheral and central inflammation was determined by qPCR of pro-inflammatory genes in fresh liver and brain. Metabolite profiles of liver, plasma and brain were determined by ¹H NMR. Endotoxin concentration in the brain was measured by the Limulus Amoebocyte Lysate (LAL) assay. Co-administration of LPS + HDL exacerbated both peripheral and central inflammation, whilst LPS + LDL attenuated this inflammation. Metabolomic analysis identified several metabolites significantly associated with LPS-induced inflammation, which were partially rescued by LDL, but not HDL. Endotoxin was detected at significantly greater concentrations in the brains of animals that received LPS + HDL compared to LPS + saline, but not those that received LPS + LDL. These results suggest that HDL may promote neuroinflammation through direct shuttling of endotoxin to the brain. In contrast, LDL was shown to have anti-neuroinflammatory properties in this study. Our results indicate that lipoproteins may be useful targets in neuroinflammation and neurodegeneration associated with endotoxemia and sepsis.

Release of nanodiscs from charged nano-droplets in the electrospray ionization revealed by molecular dynamics simulations

Electrospray ionization (ESI) is essential for application of mass spectrometry in biological systems, as it prevents the analyte being split into fragments. However, due to lack of a clear understanding of the mechanism of ESI, the interpretation of mass spectra is often ambiguous. This is a particular challenge for complex biological systems. Here, we focus on systems that include nanodiscs as membrane environment, which are essential for membrane proteins. We performed microsecond atomistic molecular dynamics simulations to study the release of nanodiscs from highly charged nano-droplets into the gas phase, the late stage of ESI. We observed two distinct major scenarios, highlighting the diversity of morphologies of gaseous product ions. Our simulations are in reasonable agreement with experimental results. Our work provides a detailed atomistic view of the ESI process of a heterogeneous system (lipid nanodisc), which may give insights into the interpretation of mass spectra of all lipid-protein systems.

Integrative omics-analysis of lipid metabolism regulation by peroxisome proliferator-activated receptor a and b agonists in male Atlantic cod

Lipid metabolism is essential in maintaining energy homeostasis in multicellular organisms. In vertebrates, the peroxisome proliferator-activated receptors (PPARs, NR1C) regulate the expression of many genes involved in these processes. Atlantic cod (Gadus morhua) is an important fish species in the North Atlantic ecosystem and in human nutrition, with a highly fatty liver. Here we study the involvement of Atlantic cod Ppar a and b subtypes in systemic regulation of lipid metabolism using two model agonists after in vivo exposure. WY-14,643, a specific PPARA ligand in mammals, activated cod Ppara1 and Ppara2 in vitro. In vivo, WY-14,643 caused a shift in lipid transport both at transcriptional and translational level in cod. However, WY-14,643 induced fewer genes in the fatty acid beta-oxidation pathway compared to that observed in rodents. Although GW501516 serves as a specific PPARB/D ligand in mammals, this compound activated cod Ppara1 and Ppara2 as well as Pparb in vitro. In vivo, it further induced transcription of Ppar target genes and caused changes in lipid composition of liver and plasma. The integrative approach provide a foundation for understanding how Ppars are engaged in regulating lipid metabolism in Atlantic cod physiology. We have shown that WY-14,643 and GW501516 activate Atlantic cod Ppara and Pparb, affect genes in lipid metabolism pathways, and induce changes in the lipid composition in plasma and liver microsomal membranes. Particularly, the combined transcriptomic, proteomics and lipidomics analyses revealed that effects of WY-14,643 on lipid metabolism are similar to what is known in mammalian studies, suggesting conservation of Ppara functions in mediating lipid metabolic processes in fish. The alterations in the lipid profiles observed after Ppar agonist exposure suggest that other chemicals with similar Ppar receptor affinities may cause disturbances in the lipid regulation of fish. Model organism: Atlantic cod (Gadus morhua). LSID: urn:lsid:zoobank.org:act:389BE401-2718-4CF2-BBAE-2E13A97A5E7B. COL Identifier: 6K72F.

Effects of Oral Carotenoids on Oxidative Stress: A Systematic Review and Meta-Analysis of Studies in the Recent 20 Years

Carotenoids protect organs, tissues, and cells from the damaging action of singlet oxygen, oxygen radicals, and lipid peroxides. This systematic review was sought to evaluate the influence of oral carotenoids on antioxidant/oxidative markers, blood carotenoids levels, and lipid/lipoprotein parameters in human subjects. A comprehensive review of relevant literature was conducted in PubMed, Web of Sciences, and the Cochrane library, from 2000 to December 2020. Randomized controlled trials, case-controlled trials, or controlled trials were identified. A total of eighteen trials were included, with the target populations being healthy subjects in 16 studies, athletes in 1 study, and pregnant women in 1 study. The meta-analysis results showed that carotenoids complex supplementation significantly increased the levels of antioxidative parameters ferric-reducing ability of plasma (FRAP) and oxygen radical absorbance capacity (ORAC) [standardized mean difference (SMD) = 0.468; 95% CI: 0.159-0.776, p = 0.003; SMD = 0.568; 95% CI: 0.190-0.947, p = 0.003] and decreased the blood triglyceride (TG) level (SMD = -0.410, 95% CI: -0.698 to -0.122, p = 0.005). Oral carotenoids supplement significantly increased the blood levels of β-carotene (SMD = 0.490, 95% CI: 0.123-0.858, p = 0.009), α-tocopherol (SMD = 0.752, 95%CI: 0.020-1.485, p = 0.044), and the intaking durations were 8 weeks. The levels of antioxidative enzymes and other lipid/lipoprotein parameters were not different between subjects receiving carotenoids and controls (p > 0.05). In conclusion, our systematic review showed that the carotenoids complex is beneficial for alleviating potential oxidative stress via interacting with free radicals or decreasing blood TG levels. The intaking duration of carotenoids should be 8 weeks to reach enough concentration for function.

Aptamer/AuNPs encoders endow precise identification and discrimination of lipoprotein subclasses

Lipoproteins are composed of lipid and apolipoproteins in conjunction with noncovalent bonds. Different lipoprotein categories, particularly Low-Density Lipoprotein (LDL), High-Density Lipoprotein (HDL) and Very Low-Density Lipoprotein (VLDL) disagree in roles for the occurrence and development of cardiovascular disease, and their exact discrimination are critically required. Herein, a multiplexed sensor platform combined with an encoder system is introduced for accurate analysis of multiple lipoproteins in complex matrix. Three encoders, i.e., bare AuNPs, AuNPs-anti-LDL aptamer (AuNPs-apt) and AuNPs-non-aptamer DNA (AuNPs-n), facilitate precise discrimination for lipoprotein subclasses at a fairly low level of 0.490 nM. The binding of single-stranded DNA (ssDNA) with AuNPs prevents them from gathering in a relatively higher level of salt. In targets stimuli, the weaker binding between ssDNA and AuNPs is destroyed to certain degrees depending on the differential affinities among DNA, AuNPs, and multifarious proteins. It results in distinct aggregation states of encoders to cause diverse ultraviolet absorption, which may be statistically characterized to achieve highly facile and precise identification for lipoprotein subclasses. Remarkably, LDL at 0.05-37.5 μg/mL could be identified by the encoder system. 11 typical proteins including three lipoprotein subclasses in human serum were also precisely discriminated. Furthermore, the accurate identification of lipoprotein subclasses with different molar ratios from real clinical serum samples were obtained.

General Protocol for Constructing Molecular Models of Nanodiscs

Nanodisc technology is increasingly being applied for structural and biophysical studies of membrane proteins. In this work, we present a general protocol for constructing molecular models of nanodiscs for molecular dynamics simulations. The protocol is written in python and based on geometric equations, making it fast and easy to modify, enabling automation and customization of nanodiscs in silico. The novelty being the ability to construct any membrane scaffold protein (MSP) variant fast and easy given only an input sequence. We validated and tested the protocol by simulating seven different nanodiscs of various sizes and with different membrane scaffold proteins, both circularized and noncircularized. The structural and biophysical properties were analyzed and shown to be in good agreement with previously reported experimental data and simulation studies.

A Salt Stimulus-Responsive Nanohydrogel for Controlled Fishing Low-Density Lipoprotein with Superior Adsorption Capacity

A salt-responsive nanoplatform is constructed through a simple tactic by tethering zwitterionic nanohydrogels (NGs) on a carboxylated silica (SiO₂-COOH) framework. Chondroitin sulfate (CS), with a specific recognition effect for low-density lipoprotein (LDL), is modified to NGs by amidation reaction. Water retention and swelling properties of NGs are greatly enhanced in a saline environment attributed to the anti-polyelectrolyte effect. It endows the SiO₂-NGs-CS framework a sensitive salt-responsive property, and thus, more CS moieties are exposed. The controlled adsorption of LDL with an adsorption efficiency of 7.2 to 93% is achieved by adjusting the concentration of MgCl₂ from 0 to 0.1 mol L^-1. SiO₂-NGs-CS exhibits excellent adsorption capacity for fishing LDL, acquiring the highest adsorption capacity of 898.1 mg g^-1. Moreover, SiO₂-NGs-CS shows superior selectivity to the other three proteins with similar isoelectric points (pIs) to LDL. The captured LDL is readily stripped by 0.2% (m/m) SDS with a recovery of 95.4%. The superior separation performance of SiO₂-NGs-CS is demonstrated by the isolation and selective discrimination of LDL from the simulated serum of hypercholesterolemia patients, as illustrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis assays.

Structure and intermolecular interactions in spheroidal high-density lipoprotein subpopulations

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High-density lipoprotein subpopulations have unique surface profiles and dynamics.

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Relative hydrophobic surface area decreases with increasing lipoprotein size.

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Core lipid exposure at the lipoprotein surface decreases with increasing size.

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Cholesterol molecules localise near apolipoprotein A-I central helices.

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Lipid and protein interactions stabilise multifoil models of apolipoprotein A-I.

Human serum high-density lipoproteins (HDLs) are a population of small, dense protein-lipid aggregates that are crucial for intravascular lipid trafficking and are protective against cardiovascular disease. The spheroidal HDL subfraction can be separated by size and density into five major subpopulations with distinct molecular compositions and unique biological functionalities: HDL_3c, HDL_3b, HDL_3a, HDL_2a and HDL_2b. Representative molecular models of these five subpopulations were developed and characterised for the first time in the presence of multiple copies of its primary protein component apolipoprotein A-I (apoA-I) using coarse-grained molecular dynamics simulations. Each HDL model exhibited size, morphological and compositional profiles consistent with experimental observables. With increasing particle size the separation of core and surface molecules became progressively more defined, resulting in enhanced core lipid mixing, reduced core lipid exposure at the surface, and the formation of an interstitial region between core and surface molecules in HDL_2b. Cholesterol molecules tended to localise around the central helix-5 of apoA-I, whilst triglyceride molecules predominantly interacted with aromatic, hydrophobic residues located within the terminal helix-10 across all subpopulation models. The three intermediate HDL models exhibited similar surface profiles despite having distinct molecular compositions. ApoA-I in trefoil, quatrefoil and pentafoil arrangements across the surface of HDL particles exhibited significant warping and twisting, but largely retained intermolecular contacts between adjacent apoA-I chains. Representative HDL subpopulations differed in particle size, morphology, intermolecular interaction profiles and lipid and protein dynamics. These findings reveal how different HDL subpopulations might exhibit distinct functional associations depending on particle size, form and composition.

Mechanistic Understanding From Molecular Dynamics Simulation in Pharmaceutical Research 1: Drug Delivery

In this review, we outline the growing role that molecular dynamics simulation is able to play as a design tool in drug delivery. We cover both the pharmaceutical and computational backgrounds, in a pedagogical fashion, as this review is designed to be equally accessible to pharmaceutical researchers interested in what this new computational tool is capable of and experts in molecular modeling who wish to pursue pharmaceutical applications as a context for their research. The field has become too broad for us to concisely describe all work that has been carried out; many comprehensive reviews on subtopics of this area are cited. We discuss the insight molecular dynamics modeling has provided in dissolution and solubility, however, the majority of the discussion is focused on nanomedicine: the development of nanoscale drug delivery vehicles. Here we focus on three areas where molecular dynamics modeling has had a particularly strong impact: (1) behavior in the bloodstream and protective polymer corona, (2) Drug loading and controlled release, and (3) Nanoparticle interaction with both model and biological membranes. We conclude with some thoughts on the role that molecular dynamics simulation can grow to play in the development of new drug delivery systems.

The emergence of new trends in clinical laboratory diagnosis

Diagnostic processes typically rely on traditional and laborious methods, that are prone to human error, resulting in frequent misdiagnosis of diseases. Computational approaches are being increasingly used for more precise diagnosis of the clinical pathology, diagnosis of genetic and microbial diseases, and analysis of clinical chemistry data. These approaches are progressively used for improving the reliability of testing, resulting in reduced diagnostic errors. Artificial intelligence (AI)-based computational approaches mostly rely on training sets obtained from patient data stored in clinical databases. However, the use of AI is associated with several ethical issues, including patient privacy and data ownership. The capacity of AI-based mathematical models to interpret complex clinical data frequently leads to data bias and reporting of erroneous results based on patient data. In order to improve the reliability of computational approaches in clinical diagnostics, strategies to reduce data bias and analyzing real-life patient data need to be further refined.

Emerging roles for high-density lipoproteins in neurodegenerative disorders

Lipoproteins are the complexes of different lipids and proteins, which are devoted to the transport and clearance of lipids or lipid-related molecules in the circulation. Lipoproteins have been found to play a crucial role in brain function and may influence myelination process. Among lipoproteins, high-density lipoproteins (HDLs) and their major protein component, apoA-I, are directly involved in cholesterol efflux in the brain. It has been suggested that inadequate or dysfunctional brain HDLs may contribute to cerebrovascular dysfunctions, neurodegeneration, or neurovascular instability. HDL deficiency could also promote cognitive decline through impacting on atherosclerotic risk. The focus of this review is to discuss knowledge on HDL dysregulation in neurological disorders. A better understanding on how changes in cellular HDL and apolipoprotein homeostasis affect central nervous system function may provide promising novel avenues for the treatment of specific HDL-related neurological disorders.

Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance

Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.

Receptor-Independent Transfer of Low Density Lipoprotein Cargo to Biomembranes

The fundamental task of lipoprotein particles is extracellular transport of cholesterol, lipids, and fatty acids. Besides, cholesterol-rich apoB-containing lipoprotein particles (i.e., low density lipoprotein LDL) are key players in progression of atherosclerotic cardiovascular disease and are associated with familial hypercholesterolemia (FH). So far, lipoprotein particle binding to the cell membrane and subsequent cargo transfer is directly linked to the lipoprotein receptors on the target cell surface. However, our observations showed that lipoprotein particle cargo transport takes place even in the absence of the receptor. This finding suggests that an alternative mechanism for lipoprotein-particle/membrane interaction, besides the receptor-mediated one, exists. Here, we combined several complementary biophysical techniques to obtain a comprehensive view on the nonreceptor mediated LDL-particle/membrane. We applied a combination of atomic force and single-molecule-sensitive fluorescence microscopy (AFM and SMFM) to investigate the LDL particle interaction with membranes of increasing complexity. We observed direct transfer of fluorescently labeled amphiphilic lipid molecules from LDL particles into the pure lipid bilayer. We further confirmed cargo transfer by fluorescence cross-correlation spectroscopy (FCCS) and spectral imaging of environment-sensitive probes. Moreover, the integration of the LDL particle into the membranes was directly visualized by high-speed atomic force microscopy (HS-AFM) and cryo-electron microscopy (cryo-EM). Overall, our data show that lipoprotein particles are able to incorporate into lipid membranes upon contact to transfer their cargo in the absence of specific receptors.

The Many Faces of Amphipathic Helices

Amphipathic helices (AHs), a secondary feature found in many proteins, are defined by their structure and by the segregation of hydrophobic and polar residues between two faces of the helix. This segregation allows AHs to adsorb at polar⁻apolar interfaces such as the lipid surfaces of cellular organelles. Using various examples, we discuss here how variations within this general scheme impart membrane-interacting AHs with different interfacial properties. Among the key parameters are: (i) the size of hydrophobic residues and their density per helical turn; (ii) the nature, the charge, and the distribution of polar residues; and (iii) the length of the AH. Depending on how these parameters are tuned, AHs can deform lipid bilayers, sense membrane curvature, recognize specific lipids, coat lipid droplets, or protect membranes from stress. Via these diverse mechanisms, AHs play important roles in many cellular processes.

Core lipid, surface lipid and apolipoprotein composition analysis of lipoprotein particles as a function of particle size in one workflow integrating asymmetric flow field-flow fractionation and liquid chromatography-tandem mass spectrometry

Lipoproteins are complex molecular assemblies that are key participants in the intricate cascade of extracellular lipid metabolism with important consequences in the formation of atherosclerotic lesions and the development of cardiovascular disease. Multiplexed mass spectrometry (MS) techniques have substantially improved the ability to characterize the composition of lipoproteins. However, these advanced MS techniques are limited by traditional pre-analytical fractionation techniques that compromise the structural integrity of lipoprotein particles during separation from serum or plasma. In this work, we applied a highly effective and gentle hydrodynamic size based fractionation technique, asymmetric flow field-flow fractionation (AF4), and integrated it into a comprehensive tandem mass spectrometry based workflow that was used for the measurement of apolipoproteins (apos A-I, A-II, A-IV, B, C-I, C-II, C-III and E), free cholesterol (FC), cholesterol esters (CE), triglycerides (TG), and phospholipids (PL) (phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and lysophosphatidylcholine (LPC)). Hydrodynamic size in each of 40 size fractions separated by AF4 was measured by dynamic light scattering. Measuring all major lipids and apolipoproteins in each size fraction and in the whole serum, using total of 0.1 ml, allowed the volumetric calculation of lipoprotein particle numbers and expression of composition in molar analyte per particle number ratios. Measurements in 110 serum samples showed substantive differences between size fractions of HDL and LDL. Lipoprotein composition within size fractions was expressed in molar ratios of analytes (A-I/A-II, C-II/C-I, C-II/C-III. E/C-III, FC/PL, SM/PL, PE/PL, and PI/PL), showing differences in sample categories with combinations of normal and high levels of Total-C and/or Total-TG. The agreement with previous studies indirectly validates the AF4-LC-MS/MS approach and demonstrates the potential of this workflow for characterization of lipoprotein composition in clinical studies using small volumes of archived frozen samples.

A giant amphipathic helix from a perilipin that is adapted for coating lipid droplets

How proteins are targeted to lipid droplets (LDs) and distinguish the LD surface from the surfaces of other organelles is poorly understood, but many contain predicted amphipathic helices (AHs) that are involved in targeting. We have focused on human perilipin 4 (Plin4), which contains an AH that is exceptional in terms of length and repetitiveness. Using model cellular systems, we show that AH length, hydrophobicity, and charge are important for AH targeting to LDs and that these properties can compensate for one another, albeit at a loss of targeting specificity. Using synthetic lipids, we show that purified Plin4 AH binds poorly to lipid bilayers but strongly interacts with pure triglycerides, acting as a coat and forming small oil droplets. Because Plin4 overexpression alleviates LD instability under conditions where their coverage by phospholipids is limiting, we propose that the Plin4 AH replaces the LD lipid monolayer, for example during LD growth.

Lipid droplets are cellular organelles important for cellular homeostasis and their disruption has been implicated in many diseases. Here the authors use a large amphipathic helix from perilipin 4 to uncover parameters important for specific lipid droplet targeting and stabilization of the oil core.

High throughput quantification of apolipoproteins A-I and B-100 by isotope dilution MS targeting fast trypsin releasable peptides without reduction and alkylation

PURPOSE

Apolipoprotein A-I (ApoA-I) and apolipoprotein B-100 (ApoB-100) are amphipathic proteins that are strong predictors of cardiovascular disease risk. The traceable calibration of apolipoprotein assays is a persistent challenge, especially for ApoB-100, which cannot be solubilized in purified form.

EXPERIMENTAL DESIGN

A simultaneous quantitation method for ApoA-I and ApoB-100 was developed using tryptic digestion without predigestion reduction and alkylation, followed by LC separation coupled with isotope dilution MS analysis. The accuracy of the method was assured by selecting structurally exposed signature peptides, optimal choice of detergent, protein:enzyme ratio, and incubation time. Peptide calibrators were value assigned by isobaric tagging isotope dilution MS amino acid analysis.

RESULTS

The method reproducibility was validated in technical repeats of three serum samples, giving 2-3% intraday CVs (N = 5) and <7% interday CVs (N = 21). The repeated analysis of interlaboratory harmonization standards showed -1% difference for ApoA-I and -12% for ApoB-100 relative to the assigned value. The applicability of the method was demonstrated by repeated analysis of 24 patient samples with a wide range of total cholesterol and triglyceride levels.

CONCLUSIONS AND CLINICAL RELEVANCE

The method is applicable for simultaneous analysis of ApoA-I and ApoB-100 in patient samples, and for characterization of serum pool calibrators for other analytical platforms.

Nanodiscs in Membrane Biochemistry and Biophysics

Membrane proteins play a most important part in metabolism, signaling, cell motility, transport, development, and many other biochemical and biophysical processes which constitute fundamentals of life on the molecular level. Detailed understanding of these processes is necessary for the progress of life sciences and biomedical applications. Nanodiscs provide a new and powerful tool for a broad spectrum of biochemical and biophysical studies of membrane proteins and are commonly acknowledged as an optimal membrane mimetic system that provides control over size, composition, and specific functional modifications on the nanometer scale. In this review we attempted to combine a comprehensive list of various applications of nanodisc technology with systematic analysis of the most attractive features of this system and advantages provided by nanodiscs for structural and mechanistic studies of membrane proteins.