共查询到20条相似文献,搜索用时 15 毫秒
1.
The microphase separation dynamics of the triblock copolymer surfactant P103 [(ethylene oxide)17(propylene oxide)60(ethylene oxide)17] was investigated by a dynamic variant of mean-field density functional theory. Different self-assembled aggregates, spherical
micelles, micellar clusters and disk-like micelles, are explored in the solution. The spherical micelle above critical micelle
concentration (CMC) is a dense core consisting mainly of PPO and a hydrated PEO swollen corona, and is in good agreement with
the experimental results concerning their structures. At a concentration of 10–15%, micellar clusters with a larger PPO core
form as a result of coalescence among spherical micelles. At concentrations above 16% by volume, a series of disk-like micelles
come into being. The order parameters show that spherical micelles are easily formed, while the micellar clusters or disk-like
micelles need a longer time to reach steady equilibrium. The results show that mesoscopic simulation can augment experimental
results on amphiphilic polymers, and provide some mesoscopic information at the mesoscale level.
Figure Coalescence of Micelles with time evolution for 15% vol system. □ represents spherical micelle that coalesce. (a) 180 μs, (b) 190 μs, (c)225 μs, and (d) 250 μs 相似文献
2.
Although reconstitution of membrane proteins within protein detergent complexes is often used to enable their structural or biophysical characterization, it is unclear how one should rationally choose the appropriate micellar environment to preserve native protein folding. Here, we investigated model mixed micelles consisting of a nonionic glucosylated alkane surfactant from the maltoside and thiomaltoside families, bile salt surfactant, and the steryl derivative cholesteryl hemisuccinate. We correlated several key attributes of these micelles with the in vitro ligand-binding activity of hA2aR in these systems. Through small-angle neutron scattering and radioligand-binding analysis, we found several key aspects of mixed micellar systems that preserve the activity of hA2aR, including a critical amount of cholesteryl hemisuccinate per micelle, and an optimal hydrophobic thickness of the micelle that is analogous to the thickness of native mammalian bilayers. These features are closely linked to the headgroup chemistry of the surfactant and the hydrocarbon chain length, which influence both the morphology and composition of resulting micelles. This study should serve as a general guide for selecting the appropriate mixed surfactant systems to stabilize membrane proteins for biophysical analysis. 相似文献
3.
Aurélie Goncalves Brigitte Gontero Marion Nowicki Marielle Margier Gabriel Masset Marie-Josèphe Amiot Emmanuelle Reboul 《Journal of lipid research》2015,56(6):1123-1133
Scavenger receptors (SRs) like cluster determinant 36 (CD36) and SR class B type I (SR-BI) play a debated role in lipid transport across the intestinal brush border membrane. We used surface plasmon resonance to analyze real-time interactions between the extracellular protein loops and various ligands ranging from single lipid molecules to mixed micelles. Micelles mimicking physiological structures were necessary for optimal binding to both the extracellular loop of CD36 (lCD36) and the extracellular loop of SR-BI (lSR-BI). Cholesterol, phospholipid, and fatty acid micellar content significantly modulated micelle binding to and dissociation from the transporters. In particular, high phospholipid micellar concentrations inhibited micelle binding to both receptors (−53.8 and −74.4% binding at 0.32 mM compared with 0.04 mM for lCD36 and lSR-BI, respectively, P < 0.05). The presence of fatty acids was crucial for micelle interactions with both proteins (94.4 and 81.3% binding with oleic acid for lCD36 and lSR-BI, respectively, P < 0.05) and fatty acid type substitution within the micelles was the component that most impacted micelle binding to the transporters. These effects were partly due to subsequent modifications in micellar size and surface electric charge, and could be correlated to micellar vitamin D uptake by Caco-2 cells. Our findings show for the first time that micellar lipid composition and micellar properties are key factors governing micelle interactions with SRs. 相似文献
4.
Monika Jurgas-Grudzinska 《Biocatalysis and Biotransformation》2013,31(3-4):293-298
The activities of horseradish peroxidase (HRP) and lactoperoxidase (LPO) entrapped in reverse micelles of Igepal CO-520 in cyclohexane were studied. When the molar ratio of water to surfactant, w0 was ≥13, the activity of HRP encapsulated in the water pool of the reverse micelle was comparable with that measured in buffer. For LPO, however, lower activity was observed after its incorporation into the same system.The activity of the investigated peroxidases was also measured in an aqueous solution of Igepal CO-720 or after incubation with this surfactant. The enzymes became inactivated in an aqueous micellar solution of Igepal CO-720, although this process was reversible.The stability of HRP and LPO at 37 or 50°C was lower in the micellar systems than in buffer with the exception for HRP in reverse micelles at 50°C. 相似文献
5.
Catia Lambertucci Sauro Vittori Ram Chandra Mishra Diego Dal Ben Karl-Norbert Klotz Rosaria Volpini 《Nucleosides, nucleotides & nucleic acids》2013,32(10-12):1443-1446
The discovery of new drugs for the treatment of neurodegenerative disorders, such as Parkinson's disease, has become an attractive field of research. Due to the regulation of D 2 receptor activity by A 2 A adenosine receptor, potent and selective ligands of A 2 A subtype could be useful tools to study neurodegenerative disorders. A series of 2,8-disubstituted-9-ethyladenine derivatives was synthesized and tested in binding affinity assay at human adenosine receptors. New compounds showed good affinity and selectivity at A 2 A receptor versus the other subtypes. The introduction of a bromine atom in 8-position increased the affinity of these compounds, leading to ligands with K i in the nanomolar range. 相似文献
6.
The topical application of all-trans retinoic acid (ATRA) is an effective treatment for several skin disorders, including photo-aging. Unfortunately, ATRA is
susceptible to light, heat, and oxidizing agents. Thus, this study aimed to investigate the ability of polymeric micelles
prepared from polyethylene glycol conjugated phosphatidylethanolamine (PEG-PE) to stabilize ATRA under various storage conditions.
ATRA entrapped in polymeric micelles with various PEG and PE structures was prepared. The critical micelle concentrations
were 97–243 μM, depending on the structures of the PEG and PE molecules. All of the micelles had particle diameters of 6–20 nm
and neutral charges. The highest entrapment efficiency (82.7%) of the tested micelles was exhibited by ATRA in PEG with a
molecular weight of 750 Da conjugated to dipalmitoyl phosphatidylethanolamine (PEG750-DPPE) micelles. The PEG750-DPPE micelle could significantly retard ATRA oxidation compared to ATRA in 75% methanol/HBS solution. Up to 87% of ATRA remained
in the PEG750-DPPE micelle solution after storage in ambient air for 28 days. This result suggests that PEG750-DPPE micelle can improve ATRA stability. Therefore, ATRA in PEG750-DPPE micelle is an interesting alternative structure for the development of cosmeceutical formulations. 相似文献
7.
2- and 8-alkynyl-9-ethyladenines: Synthesis and biological activity at human and rat adenosine receptors 总被引:1,自引:1,他引:0
Volpini R Costanzi S Lambertucci C Vittori S Martini C Trincavelli ML Klotz KN Cristalli G 《Purinergic signalling》2005,1(2):173-181
The synthesis of a series of 9-ethyladenine derivatives bearing alkynyl chains in 2- or 8-position was undertaken, based on the observation that replacement of the sugar moiety in adenosine derivatives with alkyl groups led to adenosine receptor antagonists. All the synthesized compounds were tested for their affinity at human and rat A1, A2A, and A3 adenosine receptors in binding assays; the activity at the human A2B receptor was determined in adenylyl cyclase experiments. Biological data showed that the 2-alkynyl derivatives possess good affinity and are slightly selective for the human A2A receptor. The same compounds tested on the rat A1 and A2A subtypes showed in general lower affinity for both receptors. On the other hand, the affinity of the 8-alkynyl derivatives at the human A1, A2A, and A2B receptors proved to be lower than that of the corresponding 2-alkynyl derivatives. On the contrary, the affinity of the same compounds for the human A3 receptor was improved, resulting in A3 selectivity. As in the case of the 2-alkynyl-substituted compounds, the 8-alkynyl derivatives showed decreased affinity for rat receptors. However, it is worthwhile to note that the 8-phenylethynyl-9-ethyladenine was the most active compound of the two series (Ki in the nanomolar range) at both the human and rat A3 subtype. Docking experiments of the 2- and 8-phenylethynyl-9-ethyladenines, at a rhodopsin-based homology model, gave a rational explanation of the preference of the human A3 receptor for the 8-substituted compound. 相似文献
8.
《Bioorganic & medicinal chemistry》2019,27(16):3551-3558
From a collection containing more than 1500 academic compounds, in silico screening identified a hit for the human A1 adenosine receptor containing a new purine scaffold. To study the structure activity relationships of this new chemical series for adenosine receptors, a library of 24 purines was synthesized and tested in radioligand binding assays at human A1, A2A, A2B and A3 adenosine receptor subtypes. Fourteen molecules showed potent antagonism at A1, A3 or dual A1/A3 adenosine receptors. This purine scaffold is an important source for novel biochemical tools and/or therapeutic drugs. 相似文献
9.
《Bioorganic & medicinal chemistry letters》2020,30(16):127274
Antagonists of the adenosine receptors (A1 and A2A subtypes) are widely researched as potential drug candidates for their role in Parkinson’s disease-related cognitive deficits (A1 subtype), motor dysfunction (A2A subtype) and to exhibit neuroprotective properties (A2A subtype). Previously the benzo-α-pyrone based derivative, 3-phenyl-1H-2-benzopyran-1-one, was found to display both A1 and A2A adenosine receptor affinity in the low micromolar range. Prompted by this, the α-pyrone core was structurally modified to explore related benzoxazinone and quinazolinone homologues previously unknown as adenosine receptor antagonists. Overall, the C2-substituted quinazolinone analogues displayed superior A1 and A2A adenosine receptor affinity over their C2-substituted benzoxazinone homologues. The benzoxazinones were devoid of A2A adenosine receptor binding, with only two compounds displaying A1 adenosine receptor affinity. In turn, the quinazolinones displayed varying degrees of affinity (low micromolar range) towards the A1 and A2A adenosine receptor subtypes. The highest A1 adenosine receptor affinity and selectivity were favoured by methyl para-substitution of phenyl ring B (A1Ki = 2.50 μM). On the other hand, 3,4-dimethoxy substitution of phenyl ring B afforded the best A2A adenosine receptor binding (A2AKi = 2.81 μM) among the quinazolinones investigated. In conclusion, the quinazolinones are ideal lead compounds for further structural optimization to gain improved adenosine receptor affinity, which may find therapeutic relevance in Parkinson’s disease-associated cognitive deficits and motor dysfunctions as well as exerting neuroprotective properties. 相似文献
10.
Jun Liu Guang Wei Lu Miguel Sandoval Yangzhen Ciringh Gang Xue David Jaeger Kevin Kompanik Jim Jiao Karl M. Gelotte 《AAPS PharmSciTech》2009,10(4):1216-1223
The objectives of this study were to determine the concentrations of free benzalkonium chloride (BAC) and apparent partitions coefficients (K m) in micelle solutions and to explore its application in formulation development. Ultrafiltration (UF) was carried out using 10K Nanosep® devices and centrifugation at 5,000 rpm for 5 min. The separation of free BAC from micellar solutions was also conducted using ultracentrifugation (UC) method for the comparison with UF method. Capillary electrophoresis method was used for the identification of micelles. Results showed that a UF method was applicable for quantitatively evaluating BAC–micelle interaction in micellar solutions. Unlike UF, UC could not completely separate free BAC from the micelles. The free BAC concentrations in the micelle solutions decreased with increasing surfactant concentrations. Among polysorbate 80, cremophor EL, and tyloxapol, BAC had the highest K m in polysorbate 80 solutions. The K m was significantly lower in non-buffered aqueous solutions than that in citric buffers. Moreover, increasing surfactant concentrations led to reducing antimicrobial activity. The UF is a rapid and accurate method that minimally alters the micellar equilibrium for the determination of free BAC and K m in micellar solutions. In conclusion, free BAC concentration, which is a function of surfactant type, surfactant concentration, and ion strength of solution, is likely associated with the antimicrobial activity. 相似文献
11.
Lambertucci C Cristalli G Dal Ben D Kachare DD Bolcato C Klotz KN Spalluto G Volpini R 《Purinergic signalling》2007,3(4):339-346
A new series of 2,6,9-trisubstituted adenines (5–14) have been prepared and evaluated in radioligand binding studies for their affinity at the human A1, A2A and A3 adenosine receptors and in adenylyl cyclase experiments for their potency at the human A2B subtype. From this preliminary study the conclusion can be drawn that introduction of bulky chains at the N
6 position of 9-propyladenine significantly increased binding affinity at the human A1 and A3 adenosine receptors, while the presence of a chlorine atom at the 2 position resulted in a not univocal effect, depending
on the receptor subtype and/or on the substituent present in the N
6 position. However, in all cases, the presence in the 2 position of a chlorine atom favoured the interaction with the A2A subtype. These results demonstrated that, although the synthesized compounds were found to be quite inactive at the human
A2B subtype, adenine is a useful template for further development of simplified adenosine receptor antagonists with distinct
receptor selectivity profiles. 相似文献
12.
The carboxylate amides of 8-phenyl-1,3-dimethylxanthine described herein represent a new series of selective ligands of the adenosine A2A receptors exhibiting bronchospasmolytic activity. The effects of location of 8-phenyl substitutions on the adenosine receptor (AR) binding affinities of the newly synthesized xanthines have also been studied. The compounds displayed moderate to potent binding affinities toward various adenosine receptor subtypes when evaluated through radioligand binding studies. However, most of the compounds showed the maximum affinity for the A2A subtype, some with high selectivity versus all other subtypes. Xanthine carboxylate amide 13b with a diethylaminoethylamino moiety at the para-position of the 8-phenylxanthine scaffold was identified as the most potent A2A adenosine receptor ligand with Ki = 0.06 μM. Similarly potent and highly A2A-selective are the isovanillin derivatives 16a and 16d. In addition, the newly synthesized xanthine derivatives showed good in vivo bronchospasmolytic activity when tested in guinea pigs. 相似文献
13.
《生物化学与生物物理学报:生物膜》2019,1861(4):760-767
Cholesterol has been shown to modulate the activity of multiple G Protein-coupled receptors (GPCRs), yet whether cholesterol acts through specific interactions, indirectly via modifications to the membrane, or via both mechanisms is not well understood. High-resolution crystal structures of GPCRs have identified bound cholesterols; based on a β2-adrenergic receptor (β2AR) structure bound to cholesterol and the presence of conserved amino acids in class A receptors, the cholesterol consensus motif (CCM) was identified. Here in mammalian cells expressing the adenosine A2A receptor (A2AR), ligand dependent production of cAMP is reduced following membrane cholesterol depletion with methyl-beta-cyclodextrin (MβCD), indicating that A2AR signaling is dependent on cholesterol. In contrast, ligand binding is not dependent on cholesterol depletion. All-atom molecular simulations suggest that cholesterol interacts specifically with the CCM when the receptor is in an active state, but not when in an inactive state. Taken together, the data support a model of receptor state-dependent binding between cholesterol and the CCM, which could facilitate both G-protein coupling and downstream signaling of A2AR. 相似文献
14.
Effects of Adenosine Receptor Subtypes on Hippocampal Extracellular Serotonin Level and Serotonin Reuptake Activity 总被引:2,自引:1,他引:1
Motohiro Okada Yuko Kawata Kazuhiro Kiryu Kazuhisa Mizuno Kazumaru Wada Hiroichi Tasaki Sunao Kaneko 《Journal of neurochemistry》1997,69(6):2581-2588
Abstract: To clarify the effects of adenosine receptor subtypes (A1, A2, and A3) on hippocampal serotoninergic function, hippocampal extracellular serotonin (5-HT) levels were determined by in vivo microdialysis in freely moving rats under various conditions. Both adenosine and an adenosine A1 receptor agonist, 2-chloro-N6-cyclopentyladenosine, decreased extracellular 5-HT levels, whereas an adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dimethylxanthine (CPT), and caffeine increased these levels. A selective A2A receptor agonist (CGS-21680), an adenosine A2 receptor agonist (PD-125944), an adenosine A2 receptor antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX), and an adenosine A3 receptor agonist, N6-2-(4-aminophenyl)ethyladenosine (APNEA), did not affect extracellular 5-HT levels. When the adenosine A1 receptor was blocked by CPT, the hippocampal extracellular 5-HT level was increased by adenosine, CGS-21680, and PD-125944, and decreased by caffeine, DMPX, and APNEA. When both adenosine A1 and A2 receptors were blocked by CPT and DMPX, the extracellular 5-HT level was decreased by adenosine, caffeine, and APNEA. The hippocampal extracellular 5-HT level was not affected by administration of APNEA alone, but was decreased by this agent when the adenosine A1 receptor was blocked, irrespective of whether the adenosine A2 receptor was functional. These inhibitory effects of adenosine, caffeine, and APNEA on extracellular 5-HT levels, during both adenosine A1 and A2 receptor blockade, were inhibited by selective 5-HT reuptake inhibitors. These results indicate that the stimulatory effects of the adenosine A2 receptor and the inhibitory effects of the A3 receptor on hippocampal extracellular 5-HT levels are masked by the inhibitory effects of the adenosine A1 receptor. 相似文献
15.
Elucidation of the molecular mechanisms of activation of G protein-coupled receptors (GPCRs) is among the most challenging tasks for modern membrane biology. For studies by high resolution analytical methods, these integral membrane receptors have to be expressed in large quantities, solubilized from cell membranes and purified in detergent micelles, which may result in a severe destabilization and a loss of function. Here, we report insights into differential effects of detergents, lipids and cannabinoid ligands on stability of the recombinant cannabinoid receptor CB2, and provide guidelines for preparation and handling of the fully functional receptor suitable for a wide array of downstream applications. While we previously described the expression in Escherichia coli, purification and liposome-reconstitution of multi-milligram quantities of CB2, here we report an efficient stabilization of the recombinant receptor in micelles - crucial for functional and structural characterization. The effects of detergents, lipids and specific ligands on structural stability of CB2 were assessed by studying activation of G proteins by the purified receptor reconstituted into liposomes. Functional structure of the ligand binding pocket of the receptor was confirmed by binding of 2H-labeled ligand measured by solid-state NMR. We demonstrate that a concerted action of an anionic cholesterol derivative, cholesteryl hemisuccinate (CHS) and high affinity cannabinoid ligands CP-55,940 or SR-144,528 are required for efficient stabilization of the functional fold of CB2 in dodecyl maltoside (DDM)/CHAPS detergent solutions. Similar to CHS, the negatively charged phospholipids with the serine headgroup (PS) exerted significant stabilizing effects in micelles while uncharged phospholipids were not effective. The purified CB2 reconstituted into lipid bilayers retained functionality for up to several weeks enabling high resolution structural studies of this GPCR at physiologically relevant conditions. 相似文献
16.
《Chemical Speciation and Bioavailability》2013,25(3):191-197
AbstractThe antimicrobial activity of different reverse micelles on microorganisms is been compared using the disc diffusion method. The bis (2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelle showed a more significant inhibitory effect than do other reverse. micelles, and it had an antimicrobial activity against a broad range of microorganisms. Results from an antimicrobial activity test of isooctane and a forward extraction containing soybean protein suggest that the surfactant was chiefly responsible for inhibiting microbes in AOT/isooctane reverse micelle, while isooctane hardly inhibited the microbial growth. The properties of S. aureus, cultured in the TSB with AOT reverse micellar solution, were identified by the SEM and SDS-PAGE fingerprinting of cell-wall proteins. It is concluded that the cell-wall of the S. aureus decreased in the TSB with AOT reverse micellar solution, and some cell protein subunits of the S. aureus did not occurr, especially between 14.4 and 42.7 kDa, while one new protein subunit at near 97.4 kDa occurred 相似文献
17.
Iryna Voloshyna Steven Carsons Michael J. Littlefield Jayson M. Rieger Robert Figler Allison B. Reiss 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2013,1831(2):407-416
The adenosine A2A receptor (A2AR) plays an important role in the regulation of inflammatory and immune responses. Our previous work has demonstrated that A2AR agonists exhibit atheroprotective effects by increasing expression of reverse cholesterol transport proteins in cultured human macrophages. This study explores the impact of pharmacologic activation/inhibition and gene silencing of A2AR on cholesterol homeostasis in both THP-1 human monocytes/macrophages and primary human aortic endothelial cells (HAEC). 相似文献
18.
Blad CC von Frijtag Drabbe Künzel JK de Vries H Mulder-Krieger T Bar-Yehuda S Fishman P Ijzerman AP 《Purinergic signalling》2011,7(4):453-462
We tested a panel of naturally occurring nucleosides for their affinity towards adenosine receptors. Both N
6-(2-isopentenyl)adenosine (IPA) and racemic zeatin riboside were shown to be selective human adenosine A3 receptor (hA3R) ligands with affinities in the high nanomolar range (K
i values of 159 and 649 nM, respectively). These values were comparable to the observed K
i value of adenosine on hA3R, which was 847 nM in the same radioligand binding assay. IPA also bound with micromolar affinity to the rat A3R. In a functional assay in Chinese hamster ovary cells transfected with hA3R, IPA and zeatin riboside inhibited forskolin-induced cAMP formation at micromolar potencies. The effect of IPA could be
blocked by the A3R antagonist VUF5574. Both IPA and reference A3R agonist 2-chloro-N
6-(3-iodobenzyl)adenosine-5′-N-methylcarboxamide (Cl-IB-MECA) have known antitumor effects. We demonstrated strong and highly similar antiproliferative
effects of IPA and Cl-IB-MECA on human and rat tumor cell lines LNCaP and N1S1. Importantly, the antiproliferative effect
of low concentrations of IPA on LNCaP cells could be fully blocked by the selective A3R antagonist MRS1523. At higher concentrations, IPA appeared to inhibit cell growth by an A3R-independent mechanism, as was previously reported for other A3R agonists. We used HPLC to investigate the presence of endogenous IPA in rat muscle tissue, but we could not detect the compound.
In conclusion, the antiproliferative effects of the naturally occurring nucleoside IPA are at least in part mediated by the
A3R. 相似文献
19.
Park HM Lee JH Yaoyao J Jun HJ Lee SJ 《Biochemical and biophysical research communications》2011,404(1):1094-348
Limonene is a major aromatic compound in essential oils extracted from citrus rind. The application of limonene, especially in aromatherapy, has expanded significantly, but its potential effects on cellular metabolism have been elusive. We found that limonene directly binds to the adenosine A2A receptor, which may induce sedative effects. Results from an in vitro radioligand binding assay showed that limonene exhibits selective affinity to A2A receptors. In addition, limonene increased cytosolic cAMP concentration and induced activation of protein kinase A and phosphorylation of cAMP-response element-binding protein in Chinese hamster ovary cells transfected with the human adenosine A2A receptor gene. Limonene also increased cytosolic calcium concentration, which can be achieved by the activation of adenosine A2A receptors. These findings suggest that limonene can act as a ligand and an agonist for adenosine A2A receptors. 相似文献
20.
Dal Ben D Lambertucci C Taffi S Vittori S Volpini R Cristalli G Klotz KN 《Purinergic signalling》2006,2(4):589-594
A series of 2-phenylethynyladenosine (PEAdo) derivatives substituted in the N6- and 4′-position was synthesised and the new derivatives were tested at the four human adenosine receptors stably transfected into Chinese hamster ovary (CHO) cells, using radioligand binding studies (A1, A2A, A3) or adenylyl cyclase activity assay (A2B). Binding studies showed that the presence of a phenyl ethynyl group in the 2 position of adenosine favoured the interaction with A3 receptors, resulting in compounds endowed with high affinity and selectivity for the A3 subtype. Additional substitution of the N6- and 4′-position increases both A3 affinity and selectivity. The results showed that the new compounds have a good affinity for the A3 receptor and in particular, the N6-methoxy-2-phenylethynyl-5′-N-methylcarboxamidoadenosine, with a Ki at A3 of 1.9 nM and a selectivity A1/A3 and A2A/A3 of 4,800- and 8,600-fold, respectively. Therefore, it is one of the most potent and selective agonists at the human A3 adenosine receptor subtype reported so far. Furthermore, functional assays of inhibition of 10 μM forskolin-stimulated cAMP production via the adenosine A3 receptor revealed that the new trisubstituted adenosine derivatives behave as full agonist of this receptor subtype. Docking analysis of these compounds was performed at a homology model of the human A3 receptor based on the bovine rhodopsin crystal structure as template, and the results are in accordance with the biological data.An erratum to this article can be found at 相似文献