Amphiphilic Detergent Research Articles

Frequent brushing of teeth inhibits the dissemination of the SARS-CoV-2: the biochemical mechanism.

The SARS-CoV-2 virus is primarily transmitted through direct or indirect contact with the mucous membranes of the mouth and nostrils. The presence of SARS-CoV-2 in sputum with a high viral load suggested that maintaining good oral hygiene could be critical in limiting COVID-19 disease. Brushing the teeth frequently and regularly with widely available amphiphilic detergent, sodium lauryl sulfate (SLS)-based toothpastes could help in preventing the spread of SARS-CoV-2. We proposed a community survey-based methodology followed by an in vitro biochemical strategy to test the virucidal potentiality of SLS, an amphiphilic detergent found in these toothpastes. Throughbiomolecular structureand docking analysis using modelsof spike proteinand SLS,we showed a possible molecular mechanism of action for SLS-enabled viral particle inactivation.

Hydrophobic-hydrophilic Alternation: An effective Pattern to de novo Designed Antimicrobial Peptides.

The antimicrobial peptide (AMP) is a class of molecules that are active against a variety of microorganisms, from bacterial and cancer cells to fungi. Most AMPs are natural products, as part of an organism's own defense system against harmful microbes. However, the growing prevalence of drug resistance has forced researchers to design more promising engineered antimicrobial agents. Inspired by the amphiphilic detergents, the hydrophobic-hydrophilic alternation pattern was considered to be a simple but effective way to de novo design AMPs. In this model, hydrophobic amino acids (leucine, isoleucine etc.) and hydrophilic amino acids (arginine, lysine etc.) were arranged in an alternating way in the peptide sequence. The majority of this type of peptides have a clear hydrophilic-hydrophobic interface, which allows the molecules to have good solubility in both water and organic solvents. When they come into contact with hydrophobic membranes, many peptides undergo a conformational transformation, facilitating themself to insert into the cellular envelope. Moreover, positive-charged peptide amphiphiles tended to have an affinity with negatively-charged membrane interfaces and further led to envelope damage and cell death. Herein, several typical design patterns have been reviewed. Though varying in amino acid sequence, they all basically follow the rule of alternating arrangement of hydrophilic and hydrophobic residues. Based on that, researchers synthesized some lead compounds with favorable antimicrobial activities and preliminarily investigated their possible mode of action. Besides membrane disruption, these AMPs are proven to kill microbes in multiple mechanisms. These results deepened our understanding of AMPs' design and provided a theoretical basis for constructing peptide candidates with better biocompatibility and therapeutic potential.

Fatty Acid Composition and Stoichiometry Determine the Angiogenesis Microenvironment.

The current study tested the hypothesis of whether specific lipids may control angiogenic reactions. Using the chorioallantoic membrane assay of the chick embryo, new vessel formation was analyzed quantitatively by gas chromatography and mass spectrometry as well as bioinformatics tools including an angiogenesis analyzer. Our biochemical experiments showed that a specific lipid composition and stoichiometry determine the angiogenesis microenvironment to accelerate or inhibit vessel formation. Specific lipids of angiogenesis determinants in the vessel area and the non-vessel area were identified as nitrooleic acid, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), palmitic acid, oleic acid, linoleic acid, linolenic acid, epoxyoleic acid, lysophosphatidylcholine (LPC), cholesterol, 7-ketocholesterol, and docosahexaenoyl lysophosphatidylcholine (DHA-LPC). Vessel formation happens on the surface area of the hydrophilic membrane of the yolk. Our biochemical data demonstrated that angiogenesis was followed in the white lipid complex area to generate more branches, junctions, segments, and extremities. We analyzed lipid fragments in the vessel, non-vessel, and albumen area to show that each area contains a specific lipid composition and stoichiometry. Mass spectrometry data demonstrated that the vessel area has higher concentrations of nitrooleic acid, palmitic acid, stearic acid, LPC, lysophosphatidylethanolamine, cholesterol, oleic acid, linoleic acid, 7-ketocholesterol, and DHA-LPC; however, DHA and EPA were abundant in the hydrophobic non-vessel area. The purpose of vessel formation is to wrap up the yolk area to transport nutrients including specific fatty acids. Besides, angiogenesis requires aqueous albumen shown by distance-dependent vessel formation from albumen and oxygen. Higher concentrations of fatty acids are required for energy and carbon structure from the carbon–carbon bond, membrane building blocks, and amphiphilic detergent to solubilize a hydrophobic environment in the aqueous blood layer. The current study may guide that the uncovered hydrophobic or zwitterionic molecules such as DHA and DHA-LPC may control angiogenesis as antiangiogenic or proangiogenic molecules as potential drug targets for treating uncontrolled angiogenesis-related diseases, including diabetic retinopathy and age-related macular degeneration.

Glycosylated Amphiphilic Calixarene‐Based Detergent for Functional Stabilization of Native Membrane Proteins.

AbstractStructure‐function and drug discovery studies of membrane proteins (MPs) require their extraction from cell membranes. Here we report the synthesis and use of novel glycosylated amphiphilic calixarene‐based detergent, named CALX‐173‐GK, for native membrane protein stabilization. It consists of a nonionic polar part with three saccharide groups, a calixarene ring and an aliphatic tail of seven carbon atoms. Micellization, shape and self‐assemblies were investigated. The function of three native MPs was conserved, enhanced and stabilized overtime when CALX‐173‐GK was used as a solubilization additive. Taken together, the use of this novel glycosylated amphiphilic detergent confirms the added value of combining calixarene and glycosides groups to improve functional stability of MPs. This work also illustrates the advantage of associating solubilizing and stabilizing molecules, providing a new avenue for stabilization of functional membrane proteins.

Solubilization of the serotonin1A receptor monitored utilizing membrane dipole potential

Solubilization of membrane proteins by amphiphilic detergents represents a crucial step in studies of membrane proteins in which proteins and lipids in natural membranes are dissociated giving rise to mixed clusters of proteins, lipids and detergents in the aqueous dispersion. Although solubilization is a popular method, physicochemical principles underlying solubilization are not well understood. In this work, we monitored solubilization of the bovine hippocampal serotonin1A receptor, a representative member of the GPCR family, using membrane dipole potential measured by a dual fluorescence ratiometric approach with a potential-sensitive fluorophore. Our results show that membrane dipole potential is a good indicator of solubilization and reflects the change in dipolar environment upon solubilization due to dipolar reorganization associated with solubilization. To the best of our knowledge, these results constitute the first report linking membrane dipole potential with solubilization. We envision that these results are potentially useful in providing a molecular mechanism for membrane protein solubilization.

Solubilization of G protein-coupled receptors: a convenient strategy to explore lipid-receptor interaction.

G protein-coupled receptors (GPCRs) are the largest class of molecules involved in signal transduction across cell membranes and are major drug targets. Since GPCRs are integral membrane proteins, their structure and function are modulated by membrane lipids. In particular, membrane cholesterol is an important lipid in the context of GPCR function. Solubilization of integral membrane proteins is a process in which the proteins and lipids in native membranes are dissociated in the presence of a suitable amphiphilic detergent. Interestingly, solubilization offers a convenient approach to monitor lipid-receptor interaction as it results in differential extents of lipid solubilization, thereby allowing to assess the role of specific lipids on receptor function. In this review, we highlight how this solubilization strategy is utilized to decipher novel information about the structural stringency of cholesterol necessary for supporting the function of the serotonin(1A) receptor. We envision that insight in GPCR-lipid interaction would result in better understanding of GPCR function in health and disease.

A2E: A Component of Ocular Lipofuscin¶

ABSTRACTThe presence of lipofuscin in post mitotic cells is considered a hallmark of the aging process. In the retinal pigment epithelium (RPE), lipofuscin is found as micrometer‐sized spherical particles and characterized by its yellow autofluorescence when exposed to blue light. This exposure to light is also known to produce reactive oxygen intermediates (ROI), but the particular molecular constituent(s) responsible for this phototoxicity have yet to be completely identified. Resulting mostly from the autophagocytosis of intracellular organelles, the composition of lipofuscin is poorly defined but known to contain protein, lipids and several fluorophores. The subsequent identification of one of the fluorophores in lipofuscin, A2E, generated much interest and resulted in a variety of studies to understand its potential role in the phototoxicity of lipofuscin. Several modes of toxicity have been suggested through which A2E can affect the health of RPE cells. These modes include photoinduced production of ROI, which places additional oxidative stress on RPE cells, the disruption of membrane integrity through its natural role as an amphiphilic detergent and inhibition of key cellular functions. This article presents the current understanding of the photochemistry of A2E and its involvement as a phototoxic agent in RPE cells.

A2E: a component of ocular lipofuscin.

The presence of lipofuscin in postmitotic cells is considered a hallmark of the aging process. In the retinal pigment epithelium (RPE), lipofuscin is found as micrometer-sized spherical particles and characterized by its yellow autofluorescence when exposed to blue light. This exposure to light is also known to produce reactive oxygen intermediates (ROI), but the particular molecular constituent(s) responsible for this phototoxicity have yet to be completely identified. Resulting mostly from the autophagocytosis of intracellular organelles, the composition of lipofuscin is poorly defined but known to contain protein, lipids and several fluorophores. The subsequent identification of one of the fluorophores in lipofuscin, A2E, generated much interest and resulted in a variety of studies to understand its potential role in the phototoxicity of lipofuscin. Several modes of toxicity have been suggested through which A2E can affect the health of RPE cells. These modes include photoinduced production of ROI, which places additional oxidative stress on RPE cells, the disruption of membrane integrity through its natural role as an amphiphilic detergent and inhibition of key cellular functions. This article presents the current understanding of the photochemistry of A2E and its involvement as a phototoxic agent in RPE cells.

Lipid-similar Thermal Transition of Polyethylene Glycol Alkyl Ether Detergents

A narrow, reversible endothermic main transition is found in the aqueous micellar phase of octaethylene glycol tetradecyl ether (C14E8) by DSC, characterized by a transition temperature of 41°C and a ΔH value of 0.5 kcal mol−1, which is not observed by light scattering. This transition is assigned to a cooperative conformational rearrangement of the assembled amphiphilic detergent molecules and not to a micelle aggregation process. It is suggested that the detergent’s polar head group is primarily involved in this rearrangement.

Interaction of detergents with bovine lens alpha-crystallin: evidence for an oligomeric structure based on amphiphilic interactions.

We have studied the quaternary structure of alpha-crystallin in the presence of increasing concentrations of amphiphilic and neutral detergents using gel filtration, light-scattering, boundary and equilibrium sedimentation. We observed a continuous reduction of the molar mass of the polymeric alpha-crystallin on increasing the concentration of sodium dodecyl sulphate from 0.1 mM to 5 mM, ending up with the monomeric peptides. Dodecyltrimethylammonium bromide also disrupts the oligomeric structure of alpha-crystallin but the interaction appears to be cooperative: in the sharp transition region (for a 1 mg/ml protein solution) from 3 to 8 mM of the detergent, only the native protein and a mixture of monomeric and dimeric peptide-DTAB complexes can be observed. Concomitant studies of the circular dichroism in the far UV revealed a substantial decrease of the beta-sheet and increase of the alpha-helix secondary structure. The latter can be related to the presence of amphiphilic polypeptide sequences in the constituent alpha A and alpha B peptides. These studies reveal for the first time a direct relation between changes in the secondary structure of the alpha A and alpha B peptides and the formation of the oligomeric alpha-crystallin structure: the binding of the amphiphilic detergent reduces the beta-sheet content, induces the formation of alpha-helix secondary structure and reduces the tendency of the peptide to form large aggregates. The different mechanisms for reducing the oligomeric size by anionic and cationic detergents with identical apolar parts stresses the importance of charge interactions. Our findings support some aspects of the micelle model of alpha-crystallin and can be related to its chaperone activity.

Intracellular traffic and plasma membrane secretion of small organic solutes involved in hepatocellular bile formation

Bile formation by the liver in humans involves the secretion of gram quantities of bile salts, phosphatidylcholines, and cholesterol per day. Bile salts are amphiphilic detergents capable of solubilizing membranes, and phosphatidylcholine and cholesterol are membrane constituents that are only sparingly soluble in water. Intracellular trafficking of these molecules is primarily via binding to cytosolic proteins, although vesicles may play a role. Although bile salts interact reversibly with intracellular organelles, they are secreted as monomers into bile by specific apical transport proteins. Phosphatidylcholines are derived primarily from the endoplasmic reticulum, are delivered to the inner hemileaflet of the apical membrane via cytosolic binding proteins, and are translocated to the outer hemileaflet; the mdr2 P-glycoprotein gene product is thought to play a prominent role in the last process. Cholesterol contained in plasma lipoproteins arrives either via lateral diffusion along the plasma membrane, or is released from lysosomal degradation of cholesteryl esters. Bile salts secreted into the canalicular lumen promote the formation of phospholipid vesicles on the exoplasmic face of the canalicular membrane, possibly by vesiculating microdomains of biliary-type phosphatidylcholine molecules in the outer hemileaflet. Mechanisms for cholesterol secretion into bile are as yet unknown. Intracellular trafficking and the coordinated, specific secretion of these molecules enables the massive movement of membrane-active molecules through hepatocytes, without causing damage to the cell.

Immunomodulatory effect of sodium dodecyl sulfate on human neutrophils and the human promyelocytic HL-60 cell line

The effect of sodium dodecyl sulfate (SDS), an anionic amphiphilic detergent, on the function of human neutrophils and of the human promyelocytic leukemia cell line HL-60 was investigated. SDS modulated the respiratory burst in human neutrophils and HL-60 cells which were stimulated with phorbol 12-myristate 13-acetate (PMA). In concentrations above 1 × 10 −6 M it also caused release of lysosomal enzymes (β- d-glucuronidase, myeloperoxidase and lysozyme) from neutrophils. Our results demonstrate that SDS at concentrations 1 × 10 −6 M-1 × 10 −4 M strongly affect properties of human phagocytic cells.

Amphiphilic detergents inhibit production of IgG and IgM by human peripheral blood mononuclear cells

All types (cationic, anionic and non-ionic) amphiphilic detergents significantly inhibited the production of both IgG and IgM by human peripheral blood mononuclear cells after polyclonal activation in vitro. The most potent inhibitors were didodecyldimethylammonium bromide (DDAB) and (1-methyldodecyl)dimethylamine N-oxide (2-ATDNO). They were able to suppress effectively the immunoglobulin production in 10 −3 – 10 −8 M concentrations. A medium inhibitory effect was observed with Slovapon, sodium dodecyl sulphate (SDS) and Triton X-100, while Slovanik showed an inhibition only in concentrations higher than 10 −2%. These results suggest that amphiphilic detergents may be characterized as potential immunotoxic substances with very negative effects on the immunoglobulin production.

Mixed monolayers of phosphatidylethanolamine and (laurylamido)-N,N'-dimethylpropylamine oxide at the air/water interface. Lateral proton conduction along a mixed structure of conducting and nonconducting entities

A localized lateral proton pathway is present along the phospholipid polar heads and bound water molecules when the lipids are spread in monolayers at the air/water interface. Mixed films of (laurylamino)-N-N'-dimethylpropylamine oxide (LAPOA) and phosphatidylethanolamine (PE) are studied by surface pressure and fluorescene measurements. The polar head of this amphiphilic detergent shows no global electric charge but a N + ←O - dipole. The localization of this detergent at the air/water interface changes when the mixed monolayer is compressed

Plant mitochondrial F0F1 ATP synthase. Identification of the individual subunits and properties of the purified spinach leaf mitochondrial ATP synthase.

Spinach leaf mitochondrial F0F1 ATPase has been purified and is shown to consist of twelve polypeptides. Five of the polypeptides constitute the F1 part of the enzyme. The remaining polypeptides, with molecular masses of 28 kDa, 23 kDa, 18.5 kDa, 15 kDa, 10.5 kDa, 9.5 kDa and 8.5 kDa, belong to the F0 part of the enzyme. This is the first report concerning identification of the subunits of the plant mitochondrial F0. The identification of the components is achieved on the basis of the N-terminal amino acid sequence analysis and Western blot technique using monospecific antibodies against proteins characterized in other sources. The 28-kDa protein crossreacts with antibodies against the subunit of bovine heart ATPase with N-terminal Pro-Val-Pro- which corresponds to subunit F0b of Escherichia coli F0F1. Sequence analysis of the N-terminal 32 amino acids of the 23-kDa protein reveals that this protein is similar to mammalian oligomycin-sensitivity-conferring protein and corresponds to the F1 delta subunit of the chloroplast and E. coli ATPases. The 18.5-kDa protein crossreacts with antibodies against subunit 6 of the beef heart F0 and its N-terminal sequence of 14 amino acids shows a high degree of sequence similarity to the conserved regions at N-terminus of the ATPase subunits 6 from different sources. ATPase subunit 6 corresponds to subunit F0a of the E. coli enzyme. The 15-kDa protein and the 10.5-kDa protein crossreact with antibodies against F6 and the endogenous ATPase inhibitor protein of beef heart F0F1-ATPase, respectively. The 9.5-kDa protein is an N,N'-dicyclohexylcarbodiimide-binding protein corresponding to subunit F0c of the E. coli enzyme. The 8.5-kDa protein is of unknown identity. The isolated spinach mitochondrial F0F1 ATPase catalyzes oligomycin-sensitive ATPase activity of 3.5 mumol.mg-1.min-1. The enzyme catalyzes also hydrolysis of GTP (7.5 mumol.mg-1.min-1) and ITP (4.4 mumol.mg-1.min-1). Hydrolysis of ATP was stimulated fivefold in the presence of amphiphilic detergents, however the hydrolysis of other nucleotides could not be stimulated by these agents. These results show that the plant mitochondrial F0F1 ATPase complex differs in composition from the other mitochondrial, chloroplast and bacterial ATPases. The enzyme is, however, more closely related to the yeast mitochondrial ATPase and to the animal mitochondrial ATPase than to the chloroplast enzyme. The plant mitochondrial enzyme, however, exhibits catalytic properties which are characteristic for the chloroplast enzyme.

Evidence for the presence of a carbohydrate moiety in fluorescein isothiocyanate labeled fragments of rat gastric hydrogen ion-potassium ATPase

Limited tryptic digestion of fluorescein isothiocyanate (FITC)-labeled (H+-K+)-ATPase from rat resting light gastric membranes produced a soluble 27-kDa polypeptide which retained the fluorescence of the parent enzyme. Its production was markedly enhanced in the presence of an amphiphilic detergent, Zwittergent 3-14, which potently inhibits the ATPase activity. This increase is probably due to protection of certain tryptic cleavage sites through conformational changes of the membrane enzyme by the detergent. The NH2-terminal sequence of the 27-kDa polypeptide corresponded exactly to that beginning at Asn-369 of the cDNA-deduced primary structure of the rat ATPase. The presence of the phosphorylation site, Asp-385, and FITC-labeled Lys-517, which is known to be a part of the ATP-binding site, indicates that the 27-kDa polypeptide contains a major cytoplasmic portion of (H+-K+)-ATPase. Interestingly, the polypeptide was stained with periodate-Schiff's base, indicating its glycoprotein nature. The carbohydrate group attached to the polypeptide seems to include at least an N-linked high-mannose moiety, since the polypeptide showed Con A binding activity as detected with a Con A-biotin/avidin-peroxidase assay on nitrocellulose transblots. Also, its Con A binding activity was inhibited by excess methyl alpha-D-mannopyranoside and disappeared upon treatment of the polypeptide with endoglycosidase H and N-glycanase. Further tryptic action converted the 27-kDa polypeptide to 2 smaller FITC-labeled polypeptides of 25 and 15 kDa, which lost 18 and 96 amino acid residues, respectively, from the NH2 terminus of the parent polypeptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Incorporation of biogenic amines into phospholipids studied in two-phase-system.

Phospholipids (PL) from splenic nerves, splenic nerve granules, adrenal medullary granules and egg yolk were used as binding ligands for studies on uptake of various biogenic amines. Efficient uptake of catecholamine (CA) occurred at low ionic strength (about 2-5 mM) and at pH 6.8-7.7. This uptake was also a function of the amine concentration in the aqueous medium. At higher ionic strength (e.g. 128 mM K-phosphate buffer) an uptake still occurred, but to considerably less extent, apparently since the association/dissociation ability of the amines within the PL was a function of cation concentration in the aqueous media. Sucrose- and dextrose-induced increase in the osmolarity of the aqueous medium did not to any appreciable extent reduce the CA uptake. Scatchard plot indicated that only one type of binding sites was engaged when PL from splenic nerves was used. Using PL from splenic nerves the following affinity order was obtained for the amine tested: 5-HT greater than TA greater than DA greater than NA greater than IP greater than A. When PL from medullary granules was used the order was: DA greater than IP greater than A greater than or equal to NA. No or negligible uptake of Dopa and its metabolites Doma and Dopac occurred. When added to the aqueous medium, the cationic amphiphilic detergent CTAB induced some uptake of Doma and Dopac, but no a Dopa. However, CTAB considerably diminished the uptake of NA and the other amines. On the other hand, ionic (DOC) and anionic (SDS) detergents strongly increased the uptake of NA and other amines into PL. The nonionic Triton X-100 was without significant effect on uptake of NA. It is suggested that the binding ligands may be present in the dipolar head of the PL molecules, particularly in the lipid phosphate group. The lipid protein may also be partially involved since chromatographic experiments showed that the CA accompanied lipid phosphorus and lipid protein. Electrostatic or complex interaction of CA within the polar head group or in conjunction with lipid protein would constitute an amine storage with efficient association/dissociation capacity.