scholarly journals Interaction of unsaturated fatty acids with anti-oestrogen-binding sites

1987 ◽  
Vol 243 (2) ◽  
pp. 359-364 ◽  
Author(s):  
P L H Hwang
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Binding Site ◽  
Binding Affinity ◽  
Binding Sites ◽  
Unsaturated Fatty Acids ◽  
Biological Significance ◽  
Competitive Inhibitor ◽  
Apparent Dissociation Constant ◽  
Endogenous Ligands

Specific high-affinity binding sites for non-steroidal anti-oestrogens such as tamoxifen have been identified in many animal and human tissues. The function of these binding sites and the nature of their endogenous ligands are currently unknown. Our laboratory has previously reported that unsaturated fatty acids at micromolar concentrations inhibited [3H]tamoxifen binding to the anti-oestrogen-binding sites in rat liver, raising the possibility that fatty acids might represent endogenous ligands for these sites. These studies have now been extended to examine the mechanism by which fatty acids inhibit [3H]tamoxifen binding to the anti-oestrogen-binding site. Saturation analysis revealed that increasing concentrations of oleic acid progressively decreased the apparent binding affinity of these sites for [3H]tamoxifen without decreasing the total number of binding sites; however, the apparent dissociation constant did not vary linearly with the prevailing oleic acid concentration, suggesting that the inhibition of [3H]tamoxifen binding by fatty acid was not competitive in nature. Kinetic studies of [3H]tamoxifen binding showed that oleic acid did not affect the rate of association, but increased the rate of dissociation of [3H]tamoxifen from the anti-oestrogen-binding site; the latter finding would not be expected if oleic acid acted as a competitive inhibitor. Furthermore, incubation of a rat microsomal fraction with [3H]oleic acid in the absence and presence of excess non-radioactively labelled tamoxifen also failed to demonstrate direct competition between oleic acid and tamoxifen for the same binding site. It is concluded that oleic acid, and presumably other unsaturated fatty acids, do not compete for the anti-oestrogen-binding site and probably reduce its tamoxifen-binding affinity by some other mechanism, such as perturbation of the lipid environment of the binding site. The biological significance of this interaction of unsaturated fatty acids with the anti-oestrogen-binding site remains to be elucidated.

scholarly journals Unsaturated fatty acids as endogenous inhibitors of tamoxifen binding to anti-oestrogen-binding sites

1986 ◽  
Vol 237 (3) ◽  
pp. 749-755 ◽  
Author(s):  
P L H Hwang
Keyword(s):  
Fatty Acids ◽  
Rat Liver ◽  
Binding Sites ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Biological Significance ◽  
Dependent Manner ◽  
Rat Serum ◽  
Endogenous Ligands ◽  
Serum Extract

It is known that triphenylethylene anti-oestrogens such as tamoxifen bind to specific high-affinity anti-oestrogen-binding sites, which are distinct from oestrogen receptors. These binding sites are widely distributed in human and animal tissues, but their function and endogenous ligands are unknown. By using [3H]tamoxifen and a rat liver microsomal fraction, a radio-ligand-binding assay was developed in an attempt to identify endogenous ligands for the anti-oestrogen-binding sites in the rat. An ether extract of rat serum inhibited [3H]tamoxifen binding to rat liver binding sites in a dose-dependent manner. Identification of the active serum constituents that inhibited [3H]tamoxifen binding was achieved by g.l.c.-mass spectrometry after preliminary purification of a rat serum extract by silica-gel t.l.c. Three unsaturated fatty acids (oleic, linoleic and arachidonic) accounted for about 50% of the total inhibiting activity of the serum extract. The concentrations of these fatty acids required to inhibit [3H]tamoxifen binding were in the range of 10-100 microM, comparable with those found in the rat circulation under physiological conditions. Saturated fatty acids present in rat serum (palmitic and stearic) did not inhibit [3H]tamoxifen binding. A survey of other fatty acids revealed that, in general, unsaturated fatty acids were far more potent than saturated fatty acids in inhibiting [3H]tamoxifen binding. These studies demonstrate that unsaturated fatty acids are quantitatively the most important circulating inhibitors of [3H]tamoxifen binding to the anti-oestrogen-binding sites. The biological significance of their interaction with these sites, however, remains to be clarified.

Distinct Modulation of Wild-Type and Selective Gene Mutated Vitamin D Receptor by Essential Poly Unsaturated Fatty Acids

2021 ◽  
Vol 21 ◽  
Author(s):  
Hari Balaji ◽  
Selvaraj Ayyamperuma ◽  
Niladri Saha ◽  
Shyam Sundar Pottabathula ◽  
Jubie Selvaraj ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Vitamin D ◽  
Ligand Binding ◽  
Vitamin D Deficiency ◽  
Binding Affinity ◽  
Unsaturated Fatty Acids ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Binding Energies ◽  
Wild Type

: Vitamin-D deficiency is a global concern. Gene mutations in the vitamin D receptor’s (VDR) ligand binding domain (LBD) variously alter the ligand binding affinity, heterodimerization with retinoid X receptor (RXR) and inhibit coactivator interactions. These LBD mutations may result in partial or total hormone unresponsiveness. A plethora of evidence report that selective long chain polyunsaturated fatty acids (PUFAs) including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) bind to the ligand-binding domain of VDR and lead to transcriptional activation. We therefore hypothesize that selective PUFAs would modulate the dynamics and kinetics of VDRs, irrespective bioactive of vitamin-D binding. The spatial arrangements of the selected PUFAs in VDR active site were examined by in-silico docking studies. The docking results revealed that PUFAs have fatty acid structure-specific binding affinity towards VDR. The calculated EPA, DHA & AA binding energies (Cdocker energy) were lesser compared to vitamin-D in wild type of VDR (PDB id: 2ZLC). Of note, the DHA has higher binding interactions to the mutated VDR (PDB id: 3VT7) when compared to the standard Vitamin-D. Molecular dynamic simulation was utilized to confirm the stability of potential compound binding of DHA with mutated VDR complex. These findings suggest the unique roles of PUFAs in VDR activation and may offer alternate strategy to circumvent vitamin-D deficiency.

scholarly journals Study of Endogen Substrates, Drug Substrates and Inhibitors Binding Conformations on MRP4 and Its Variants by Molecular Docking and Molecular Dynamics

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1051
Author(s):  
Edgardo Becerra ◽  
Giovanny Aguilera-Durán ◽  
Laura Berumen ◽  
Antonio Romo-Mancillas ◽  
Guadalupe García-Alcocer
Keyword(s):  
Molecular Dynamics ◽  
Molecular Docking ◽  
Binding Energy ◽  
Binding Site ◽  
Binding Sites ◽  
Adenosine Monophosphate ◽  
Competitive Inhibitor ◽  
Umbrella Sampling ◽  
Coarse Grained ◽  
Nucleotide Polymorphisms

Multidrug resistance protein-4 (MRP4) belongs to the ABC transporter superfamily and promotes the transport of xenobiotics including drugs. A non-synonymous single nucleotide polymorphisms (nsSNPs) in the ABCC4 gene can promote changes in the structure and function of MRP4. In this work, the interaction of certain endogen substrates, drug substrates, and inhibitors with wild type-MRP4 (WT-MRP4) and its variants G187W and Y556C were studied to determine differences in the intermolecular interactions and affinity related to SNPs using protein threading modeling, molecular docking, all-atom, coarse grained, and umbrella sampling molecular dynamics simulations (AA-MDS and CG-MDS, respectively). The results showed that the three MRP4 structures had significantly different conformations at given sites, leading to differences in the docking scores (DS) and binding sites of three different groups of molecules. Folic acid (FA) had the highest variation in DS on G187W concerning WT-MRP4. WT-MRP4, G187W, Y556C, and FA had different conformations through 25 ns AA-MD. Umbrella sampling simulations indicated that the Y556C-FA complex was the most stable one with or without ATP. In Y556C, the cyclic adenosine monophosphate (cAMP) and ceefourin-1 binding sites are located out of the entrance of the inner cavity, which suggests that both cAMP and ceefourin-1 may not be transported. The binding site for cAMP and ceefourin-1 is quite similar and the affinity (binding energy) of ceefourin-1 to WT-MRP4, G187W, and Y556C is greater than the affinity of cAMP, which may suggest that ceefourin-1 works as a competitive inhibitor. In conclusion, the nsSNPs G187W and Y556C lead to changes in protein conformation, which modifies the ligand binding site, DS, and binding energy.

scholarly journals Inhibition of steroid 5α-reductase by specific aliphatic unsaturated fatty acids

1992 ◽  
Vol 285 (2) ◽  
pp. 557-562 ◽  
Author(s):  
T Liang ◽  
S Liao
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Linoleic Acid ◽  
Linolenic Acid ◽  
Unsaturated Fatty Acids ◽  
Binding Assay ◽  
Reductase Activity ◽  
Undecylenic Acid ◽  
Gamma Linolenic Acid ◽  
Enzymic Assay

Human or rat microsomal 5 alpha-reductase activity, as measured by enzymic conversion of testosterone into 5 alpha-dihydrotestosterone or by binding of a competitive inhibitor, [3H]17 beta-NN-diethulcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one ([3H]4-MA) to the reductase, is inhibited by low concentrations (less than 10 microM) of certain polyunsaturated fatty acids. The relative inhibitory potencies of unsaturated fatty acids are, in decreasing order: gamma-linolenic acid greater than cis-4,7,10,13,16,19-docosahexaenoic acid = cis-6,9,12,15-octatetraenoic acid = arachidonic acid = alpha-linolenic acid greater than linoleic acid greater than palmitoleic acid greater than oleic acid greater than myristoleic acid. Other unsaturated fatty acids such as undecylenic acid, erucic acid and nervonic acid, are inactive. The methyl esters and alcohol analogues of these compounds, glycerols, phospholipids, saturated fatty acids, retinoids and carotenes were inactive even at 0.2 mM. The results of the binding assay and the enzymic assay correlated well except for elaidic acid and linolelaidic acid, the trans isomers of oleic acid and linoleic acid respectively, which were much less active than their cis isomers in the binding assay but were as potent in the enzymic assay. gamma-Linolenic acid had no effect on the activities of two other rat liver microsomal enzymes: NADH:menadione reductase and glucuronosyl transferase. gamma-Linolenic acid, the most potent inhibitor tested, decreased the Vmax. and increased Km values of substrates, NADPH and testosterone, and promoted dissociation of [3H]4-MA from the microsomal reductase. gamma-Linolenic acid, but not the corresponding saturated fatty acid (stearic acid), inhibited the 5 alpha-reductase activity, but not the 17 beta-dehydrogenase activity, of human prostate cancer cells in culture. These results suggest that unsaturated fatty acids may play an important role in regulating androgen action in target cells.

scholarly journals Antioxidant and fatty acid profile of gabiroba seed (Campomanesisa Xanthocarpa Berg)

2012 ◽  
Vol 32 (2) ◽  
pp. 234-238 ◽  
Author(s):  
Marli da Silva Santos ◽  
Obdulio Gomes Miguel ◽  
Carmen Lúcia Oliveira Petkowicz ◽  
Lys Mary Bileski Cândido
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Unsaturated Fatty Acids ◽  
Ethanol Extract ◽  
Solvent Polarity ◽  
Antioxidant Potential ◽  
Total Phenolic ◽  
Total Phenolic Compounds

This study aimed to evaluate the antioxidant potential and fatty acid profile of gabiroba (Campomanesia xanthocarpa Berg) seeds. In order to obtain the extract, the seeds were dried, crushed, and subjected to sequential extraction by maceration and percolation in a modified soxhlet extractor using solvent polarity gradient composed of hexane, chloroform, ethyl acetate, and alcohol, respectively. The extraction time was six hours. The ethanol extract showed the highest antioxidant potential, given by the EC50 value and the amount of total phenolic compounds. High amounts of unsaturated fatty acids were found in the oil studied, especially the oleic acid.

scholarly journals Effect of nitrogen and potassium fertilization on the production and quality of oil in Jatropha curcas L. under the dry and warm climate conditions of Colombia

2014 ◽  
Vol 32 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Omar Montenegro R. ◽  
Stanislav Magnitskiy ◽  
Martha C. Henao T.
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Jatropha Curcas ◽  
Oil Content ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Fruit Production ◽  
Biodiesel Production ◽  
Oil Composition

This study was conducted to assess fruit and seed yield, oil content and oil composition of Jatropha curcas fertilized with different doses of nitrogen and potassium in Espinal (Tolima, Colombia). The yields ranged from 4,570 to 8,800 kg ha-1 of fruits and from 2,430 to 4,746 kg ha-1 of seeds. These yields showed that the fertilizer dose of 150 kg ha-1 N + 120 kg ha-1K increased fruit production by 92% and seed production by 95%, which represents an increase of about 100% in oil production, which increased from 947 to 1,900 kg ha-1. The total oil content in the seeds ranged from 38.7 to 40.1% (w/w) with a high content of the unsaturated fatty acids oleic (> 47%) and linoleic acid (> 29%). The highest content of oleic acid in the seed oil was from the unfertilized control plants and plants with an application of 100 kg ha-1 of N and 60 kg ha-1 of K, with an average of 48%. The lowest content of oleic acid was registered when a low dose of nitrogen and a high level of potassium were applied at a ratio of 1:2.4 and doses of 50 kg ha-1 N + 120 kg ha-1 K, respectively. Low contents of the saturated fatty acids palmitic (13.4%) and stearic (7.26%) were obtained, making this oil suitable for biodiesel production. The nitrogen was a more important nutrient for the production and quality of oil in J. curcas than potassium under the studied conditions of soil and climate.

scholarly journals Antagonism Between Saturated and Unsaturated Fatty Acids in ROS Mediated Lipotoxicity in Rat Insulin-Producing Cells

2015 ◽  
Vol 36 (3) ◽  
pp. 852-865 ◽  
Author(s):  
Wiebke Gehrmann ◽  
Wiebke Würdemann ◽  
Thomas Plötz ◽  
Anne Jörns ◽  
Sigurd Lenzen ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Palmitic Acid ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
H2o2 Production ◽  
Β Cell ◽  
Specific Expression ◽  
Insulin Producing Cells ◽  
H2o2 Formation

Background/Aims: Elevated levels of non-esterified fatty acids (NEFAs) are under suspicion to mediate β-cell dysfunction and β-cell loss in type 2 diabetes, a phenomenon known as lipotoxicity. Whereas saturated fatty acids show a strong cytotoxic effect upon insulin-producing cells, unsaturated fatty acids are not toxic and can even prevent toxicity. Experimental evidence suggests that oxidative stress mediates lipotoxicity and there is evidence that the subcellular site of ROS formation is the peroxisome. However, the interaction between unsaturated and saturated NEFAs in this process is unclear. Methods: Toxicity of rat insulin-producing cells after NEFA incubation was measured by MTT and caspase assays. NEFA induced H2O2 formation was quantified by organelle specific expression of the H2O2 specific fluorescence sensor protein HyPer. Results: The saturated NEFA palmitic acid had a significant toxic effect on the viability of rat insulin-producing cells. Unsaturated NEFAs with carbon chain lengths >14 showed, irrespective of the number of double bonds, a pronounced protection against palmitic acid induced toxicity. Palmitic acid induced H2O2 formation in the peroxisomes of insulin-producing cells. Oleic acid incubation led to lipid droplet formation, but in contrast to palmitic acid induced neither an ER stress response nor peroxisomal H2O2 generation. Furthermore, oleic acid prevented palmitic acid induced H2O2 production in the peroxisomes. Conclusion: Thus unsaturated NEFAs prevent deleterious hydrogen peroxide generation during peroxisomal β-oxidation of long-chain saturated NEFAs in rat insulin-producing cells.

ERUCIC ACID AND CHOLESTEROL EXCRETION IN THE RAT

1956 ◽  
Vol 34 (1) ◽  
pp. 981-991 ◽  
Author(s):  
K. K. Carroll ◽  
R. L. Noble
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Erucic Acid ◽  
Unsaturated Fatty Acids ◽  
Fatty Acid Fraction ◽  
Cholesterol Concentration ◽  
Acid Fraction ◽  
Cholesterol Excretion ◽  
Fecal Cholesterol

Erucic acid has been found to increase the excretion of endogenously produced cholesterol in the rat with little change in the cholesterol concentration in the carcass except for increased concentrations in the adrenals and liver. The fecal cholesterol was identified by melting point and infrared spectrum after isolation by chromatography on alumina. It does not appear to originate in the liver since no increase was observed in the biliary excretion of cholesterol. Other homologues of oleic acid, namely eicosenoic and nervonic acid, produced similar changes in fecal cholesterol excretion, although oleic acid itself had little effect. A series of saturated fatty acids from butyric (C4) to behenic (C22) were tested and the longer chain members found to cause some increase in cholesterol excretion. Ester cholesterol accounted for much of the observed increases but varied greatly in the experiments with unsaturated fatty acids. A preparation of cerebrosides from beef spinal cord also increased the amount of cholesterol excreted in the feces. The fatty acid fraction from this preparation gave a similar result, although the cerebrosides gave rise mainly to free cholesterol and the fatty acid fraction to ester cholesterol.

scholarly journals Structural and Functional Characterization of Host FHL1 Protein Interaction with Hypervariable Domain of Chikungunya Virus nsP3 Protein

2020 ◽  
Vol 95 (1) ◽  
Author(s):  
Tetyana Lukash ◽  
Tatiana Agback ◽  
Francisco Dominguez ◽  
Nikita Shiliaev ◽  
Chetan Meshram ◽  
...  
Keyword(s):  
Viral Replication ◽  
Binding Site ◽  
Cell Lines ◽  
Binding Sites ◽  
Chikungunya Virus ◽  
Biological Significance ◽  
Host Factors ◽  
Published Data ◽  
Wide Range ◽  
Infection Spread

ABSTRACT Decades of insufficient control have resulted in unprecedented spread of chikungunya virus (CHIKV) around the globe, and millions have suffered from the highly debilitating disease. Nevertheless, the current understanding of CHIKV-host interactions and adaptability of the virus to replication in mosquitoes and mammalian hosts is still elusive. Our new study shows that four-and-a-half LIM domain protein (FHL1) is one of the host factors that interact with the hypervariable domain (HVD) of CHIKV nsP3. Unlike G3BPs, FHL1 is not a prerequisite of CHIKV replication, and many commonly used cell lines do not express FHL1. However, its expression has a detectable stimulatory effect(s) on CHIKV replication, and Fhl1 knockout (KO) cell lines demonstrate slower infection spread. Nuclear magnetic resonance (NMR)-based studies revealed that the binding site of FHL1 in CHIKV nsP3 HVD overlaps that of another proviral host factor, CD2AP. The structural data also demonstrated that FHL1-HVD interaction is mostly determined by the LIM1 domain of FHL1. However, it does not mirror binding of the entire protein, suggesting that other LIM domains are involved. In agreement with previously published data, our biological experiments showed that interactions of CHIKV HVD with CD2AP and FHL1 have additive effects on the efficiency of CHIKV replication. This study shows that CHIKV mutants with extensive modifications of FHL1- or both FHL1- and CD2AP-binding sites remain viable and develop spreading infection in multiple cell types. Our study also demonstrated that other members of the FHL family can bind to CHIKV HVD and thus may be involved in viral replication. IMPORTANCE Replication of chikungunya virus (CHIKV) is determined by a wide range of host factors. Previously, we have demonstrated that the hypervariable domain (HVD) of CHIKV nsP3 contains linear motifs that recruit defined families of host proteins into formation of functional viral replication complexes. Now, using NMR-based structural and biological approaches, we have characterized the binding site of the cellular FHL1 protein in CHIKV HVD and defined the biological significance of this interaction. In contrast to previously described binding of G3BP to CHIKV HVD, the FHL1-HVD interaction was found to not be a prerequisite of viral replication. However, the presence of FHL1 has a stimulatory effect on CHIKV infectivity and, subsequently, the infection spread. FHL1 and CD2AP proteins were found to have overlapping binding sites in CHIKV HVD and additive proviral functions. Elimination of the FHL1-binding site in the nsP3 HVD can be used for the development of stable, attenuated vaccine candidates.

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