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The Journal of Physical Chemistry. B Oct 2013The basic amino acids lysine (Lys) and arginine (Arg) play important roles in membrane protein activity, the sensing of membrane voltages, and the actions of...
The basic amino acids lysine (Lys) and arginine (Arg) play important roles in membrane protein activity, the sensing of membrane voltages, and the actions of antimicrobial, toxin, and cell-penetrating peptides. These roles are thought to stem from the strong interactions and disruptive influences of these amino acids on lipid membranes. In this study, we employ fully atomistic molecular dynamics simulations to observe, quantify, and compare the interactions of Lys and Arg with saturated phosphatidylcholine membranes of different thickness. We make use of both charged (methylammonium and methylguanidinium) and neutral (methylamine and methylguanidine) analogue molecules, as well as Lys and Arg side chains on transmembrane helix models. We find that the free energy barrier experienced by a charged Lys crossing the membrane is strikingly similar to that of a charged Arg (to within 2 kcal/mol), despite the two having different chemistries, H-bonding capability, and hydration free energies that differ by ∼10 kcal/mol. In comparison, the barrier for neutral Arg is higher than that for neutral Lys by around 5 kcal/mol, being more selective than that for the charged species. This can be explained by the different transport mechanisms for charged or neutral amino acid side chains in the membrane, involving membrane deformations or simple dehydration, respectively. As a consequence, we demonstrate that Lys would be deprotonated in the membrane, whereas Arg would maintain its charge. Our simulations also reveal that Arg attracts more phosphate and water in the membrane, and can form extensive H-bonding with its five H-bond donors to stabilize Arg-phosphate clusters. This leads to enhanced interfacial binding and membrane perturbations, including the appearance of a trans-membrane pore in a thinner membrane. These results highlight the special role played by Arg as an amino acid to bind to, disrupt, and permeabilize lipid membranes, as well as to sense voltages for a range of peptide and protein activities in nature and in engineered bionanodevices.
Topics: 1,2-Dipalmitoylphosphatidylcholine; Arginine; Hydrogen Bonding; Hydrogen-Ion Concentration; Lysine; Membrane Lipids; Methylamines; Methylguanidine; Molecular Dynamics Simulation; Proteins; Thermodynamics
PubMed: 24007457
DOI: 10.1021/jp405418y -
Journal of Biomedical Science Feb 2009Increased reactive oxygen species (ROS) and hyperlipidemia can promote arterial thrombus. We evaluated the potential of a partially hydrolyzed guar gum (PHGG) as dietary...
Partially hydrolyzed guar gum supplement reduces high-fat diet increased blood lipids and oxidative stress and ameliorates FeCl3-induced acute arterial injury in hamsters.
Increased reactive oxygen species (ROS) and hyperlipidemia can promote arterial thrombus. We evaluated the potential of a partially hydrolyzed guar gum (PHGG) as dietary fiber on lipid profiles and FeCl3-induced arterial thrombosis in the high fat-diet fed hamsters. Our in vitro results found that PHGG is efficient to scavenge O2-*, H2O2, and HOCl. High fat-diet increased plasma triglyceride, total cholesterol, LDL, VLDL, methylguanidine and dityrosine level and accelerated FeCl3-induced arterial thrombosis formation (from 463 +/- 51 to 303 +/- 45 sec). Low dose PHGG supplement significantly decreased the total cholesterol, LDL, methylguanidine and dityrosine level and delayed the time for arterial thrombosis formation (528 +/- 75 sec). High dose PHGG supplement decreased the level in triglyceride, total cholesterol, LDL and VLDL and further delayed the time for arterial thrombus (671 +/- 36 sec). The increased Bax protein and decreased Bcl-2 and HSP-70 protein expression was found in the carotid and femoral arteries of high fat-diet hamsters. Low and high dose of PHGG supplement decreased Bax expression and increased Bcl-2 and HSP-70 protein expression. We found that FeCl3 significantly enhanced intercellular adhesion molecule-1 and 4-hydroxynonenal expression in the endothelial site of damaged artery after 150-sec FeCl3 stimulation. PHGG supplement decreased the endothelial ICAM-1 and 4-hydroxynonenal expression after 150-sec FeCl3 stimulation. Based on these results, we conclude that PHGG supplement can increase antioxidant protein expression and thus decrease oxidative stress induced arterial injury.
Topics: Aldehydes; Animals; Antioxidants; Arteries; Body Weight; Carbohydrate Conformation; Carbohydrate Sequence; Cricetinae; Dietary Fats; Dietary Supplements; Eating; Free Radical Scavengers; Galactans; HSP70 Heat-Shock Proteins; Humans; Intercellular Adhesion Molecule-1; Iron Compounds; Lipids; Male; Mannans; Mesocricetus; Molecular Sequence Data; Molecular Structure; Oxidative Stress; Plant Gums; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Thrombosis; bcl-2-Associated X Protein
PubMed: 19272178
DOI: 10.1186/1423-0127-16-15 -
Clinical Journal of the American... Aug 2022Adsorption of uremic solutes to activated carbon provides a potential means to limit dialysate volumes required for new dialysis systems. The ability of activated carbon...
BACKGROUND AND OBJECTIVES
Adsorption of uremic solutes to activated carbon provides a potential means to limit dialysate volumes required for new dialysis systems. The ability of activated carbon to take up uremic solutes has, however, not been adequately assessed.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS
Graded volumes of waste dialysate collected from clinical hemodialysis treatments were passed through activated carbon blocks. Metabolomic analysis assessed the adsorption by activated carbon of a wide range of uremic solutes. Additional experiments tested the ability of the activated carbon to increase the clearance of selected solutes at low dialysate flow rates.
RESULTS
Activated carbon initially adsorbed the majority, but not all, of 264 uremic solutes examined. Solute adsorption fell, however, as increasing volumes of dialysate were processed. Moreover, activated carbon added some uremic solutes to the dialysate, including methylguanidine. Activated carbon was particularly effective in adsorbing uremic solutes that bind to plasma proteins. dialysis experiments showed that introduction of activated carbon into the dialysate stream increased the clearance of the protein-bound solutes indoxyl sulfate and p-cresol sulfate by 77%±12% (mean±SD) and 73%±12%, respectively, at a dialysate flow rate of 200 ml/min, but had a much lesser effect on the clearance of the unbound solute phenylacetylglutamine.
CONCLUSIONS
Activated carbon adsorbs many but not all uremic solutes. Introduction of activated carbon into the dialysate stream increased the clearance of those solutes that it does adsorb.
Topics: Charcoal; Dialysis Solutions; Humans; Indican; Protein Binding; Renal Dialysis; Uremia
PubMed: 35835518
DOI: 10.2215/CJN.01610222 -
Beilstein Journal of Organic Chemistry 2021Chemical modifications have been extensively used for therapeutic oligonucleotides because they strongly enhance the stability against nucleases, binding affinity to the...
Chemical modifications have been extensively used for therapeutic oligonucleotides because they strongly enhance the stability against nucleases, binding affinity to the targets, and efficacy. We previously reported that oligonucleotides modified with an -methylguanidine-bridged nucleic acid (GuNA[Me]) bearing the thymine (T) nucleobase show excellent biophysical properties for applications in antisense technology. In this paper, we describe the synthesis of GuNA[Me] phosphoramidites bearing other typical nucleobases including adenine (A), guanine (G), and 5-methylcytosine (C). The phosphoramidites were successfully incorporated into oligonucleotides following the method previously developed for the GuNA[Me]-T-modified oligonucleotides. The binding affinity of the oligonucleotides modified with GuNA[Me]-A, -G, or -C toward the complementary single-stranded DNAs or RNAs was systematically evaluated. All of the GuNA[Me]-modified oligonucleotides were found to have a strong affinity for RNAs. These data indicate that GuNA[Me] could be a useful modification for therapeutic antisense oligonucleotides.
PubMed: 33747234
DOI: 10.3762/bjoc.17.54 -
Neuropharmacology Dec 2019Poly(ADP-ribose) polymerase-1 (PARP1) is a ubiquitous nuclear enzyme that regulates DNA repair and genomic stability. In oxidative genotoxic conditions, PARP1 activity...
Poly(ADP-ribose) polymerase-1 (PARP1) is a ubiquitous nuclear enzyme that regulates DNA repair and genomic stability. In oxidative genotoxic conditions, PARP1 activity is enhanced significantly, leading to excessive depletion of nicotinamide adenine dinucleotide (NAD) and mitochondrial dysfunction. We hypothesized that PARP1-induced NAD depletion inhibits NAD-dependent sirtuin deacetylase activity, thereby interfering with the mitochondrial regulator, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). The DNA alkylator, N'-Nitro-N-nitroso-N-methylguanidine (MNNG), induced NAD depletion, inhibited sirtuin deacetylase activity and enhanced acetylation of PGC-1α. This was associated with reduced interaction between PGC-1α and nuclear respiratory factor 1 (NRF-1), which is a nuclear transcription factor that drives mitochondrial replication by regulating mitochondrial transcription factor A (TFAM). MNNG also reduced binding of NRF-1 to the tfam upstream promoter region and reduced TFAM mRNA, mitochondrial DNA copy number and respiratory function. MNNG effects were mitigated by PARP1 inhibition and genetic loss of function, by enhancing intracellular NAD levels, and with sirtuin (SIRT1) gain of function, supporting a mechanism dependent on PARP1 activity, NAD-depletion and SIRT1 inhibition. This and other work from our group supports a destructive sequelae of events related to PARP1-induced sirtuin inhibition and sirtuin-mediated regulation of transcription.
Topics: Acetylation; Animals; Cell Respiration; DNA, Mitochondrial; DNA-Binding Proteins; High Mobility Group Proteins; Methylnitronitrosoguanidine; Mice; Mitochondria; NAD; Neurons; Nuclear Respiratory Factor 1; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Poly (ADP-Ribose) Polymerase-1; Sirtuin 1; Transcription Factors; Transcription, Genetic
PubMed: 31487495
DOI: 10.1016/j.neuropharm.2019.107755 -
Kidney International Aug 2003Increased oxidative stress in end-stage renal disease (ESRD) patients may oxidize macromolecules and consequently lead to cardiovascular events during chronic...
BACKGROUND
Increased oxidative stress in end-stage renal disease (ESRD) patients may oxidize macromolecules and consequently lead to cardiovascular events during chronic hemodialysis. Electrolyzed reduced water (ERW) with reactive oxygen species (ROS) scavenging ability may have a potential effect on reduction of hemodialysis-induced oxidative stress in ESRD patients.
METHODS
We developed a chemiluminescence emission spectrum and high-performance liquid chromatography analysis to assess the effect of ERW replacement on plasma ROS (H2O2 and HOCl) scavenging activity and oxidized lipid or protein production in ESRD patients undergoing hemodialysis. Oxidized markers, dityrosine, methylguanidine, and phosphatidylcholine hydroperoxide, and inflammatory markers, interleukin 6 (IL-6), and C-reactive protein (CRP) were determined.
RESULTS
Although hemodialysis efficiently removes dityrosine and creatinine, hemodialysis increased oxidative stress, including phosphatidylcholine hydroperoxide, and methylguanidine. Hemodialysis reduced the plasma ROS scavenging activity, as shown by the augmented reference H2O2 and HOCl counts (Rh2o2 and Rhocl, respectively) and decreased antioxidative activity (expressed as total antioxidant status in this study). ERW administration diminished hemodialysis-enhanced Rh2o2 and Rhocl, minimized oxidized and inflammatory markers (CRP and IL-6), and partly restored total antioxidant status during 1-month treatment.
CONCLUSION
This study demonstrates that hemodialysis with ERW administration may efficiently increase the H2O2- and HOCl-dependent antioxidant defense and reduce H2O2- and HOCl-induced oxidative stress.
Topics: Adult; Amino Acids; Antioxidants; C-Reactive Protein; Chromatography, High Pressure Liquid; Electrolysis; Electrolytes; Female; Humans; Interleukin-6; Kidney Failure, Chronic; Lipid Peroxidation; Luminescent Measurements; Male; Middle Aged; Oxidation-Reduction; Oxidative Stress; Renal Dialysis; Water
PubMed: 12846769
DOI: 10.1046/j.1523-1755.2003.00118.x -
Metabolites Nov 2020Autism spectrum disorder is a heterogeneous neurodevelopmental disease. Currently, no biomarker of this disease is known. Diagnosis is performed through observation,...
Autism spectrum disorder is a heterogeneous neurodevelopmental disease. Currently, no biomarker of this disease is known. Diagnosis is performed through observation, standardized behavioral scales, and interviews with parents. In practice, diagnosis is often delayed to the average age of four years or even more which adversely affects a child's perspective. A laboratory method allowing to detect the disorder at earlier stages is of a great need, as this could help the patients to start with treatment at a younger age, even prior to the clinical diagnosis. Recent evidence indicates that metabolomic markers should be considered as diagnostic markers, also serving for further differentiation and characterization of different subgroups of the autism spectrum. In this study, we developed an ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry method for the simultaneous determination of six metabolites in human urine. These metabolites, namely methylguanidine, N-acetyl arginine, inosine, indole-3-acetic acid, indoxyl sulfate and xanthurenic acid were selected as potential biomarkers according to prior metabolomic studies. The analysis was carried out by means of reversed-phase liquid chromatography with gradient elution. Separation of the metabolites was performed on a Phenomenex Luna Omega Polar C18 (100 × 1.0 mm, 1.6 µm) column at a flow rate of 0.15 mL/min with acetonitrile/water 0.1% formic acid aqueous as the mobile phase. The analysis was performed on a group of children with autism spectrum disorder and age-matched controls. In school children, we have detected disturbances in the levels of oxidative stress markers connected to arginine and purine metabolism, namely methylguanidine and N-acetylargine. Also, products of gut bacteria metabolism, namely indoxyl sulfate and indole-3-acetic acid, were found to be elevated in the patients' group. We can conclude that this newly developed method is fast, sensitive, reliable, and well suited for the quantification of proposed markers.
PubMed: 33147863
DOI: 10.3390/metabo10110443 -
Kidney International Sep 1974
Topics: Animals; Creatinine; Dogs; Guanidines; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Peritoneal Dialysis; Protein Binding; Renal Dialysis; Urea; Uremia
PubMed: 4425483
DOI: 10.1038/ki.1974.96 -
Kidney International Mar 1994Aminoguanidine, NG-monomethyl-L-arginine (L-NMMA), NGNGdimethyl-L-arginine (asymmetric dimethylarginine; ADMA), creatinine, guanidinosuccinic acid, guanidinoproprionic...
Aminoguanidine, NG-monomethyl-L-arginine (L-NMMA), NGNGdimethyl-L-arginine (asymmetric dimethylarginine; ADMA), creatinine, guanidinosuccinic acid, guanidinoproprionic acid and methylguanidine were added to cultures of activated murine macrophages. Only aminoguanidine, ADMA, L-NMMA and methylguanidine inhibited nitrite production in a dose-dependent manner. In the presence of 100 microM arginine, nitrite production was inhibited by 31.8 +/- 7.1% by ADMA (100 microM; P < 0.01) but the same dose of methylguanidine was without effect. A higher dose of methylguanidine (1000 microM) inhibited nitrite production by 47.6 +/- 5.6% (P < 0.001). The effects of these compounds were also tested on relaxation of human saphenous veins. L-NMMA and ADMA inhibited endothelium-dependent relaxations (EC50 = 4.7 +/- 1.1 microM and 17.9 +/- 4.9 microM, respectively); methylguanidine caused endothelium-independent contractions and reversed the relaxations to bradykinin and sodium nitroprusside (EC50 > 100 microM); aminoguanidine was without effect. The results of this study suggest that of the guanidino compounds which accumulate in renal failure, only ADMA is a potent inhibitor of nitric oxide (NO) synthesis. Methylguanidine is a weak inhibitor of nitric oxide synthesis, whereas the closely related compound aminoguanidine appears to inhibit selectively the inducible isoform of nitric oxide synthase and has no effect on constitutive NO synthase in human veins.
Topics: Amino Acid Oxidoreductases; Animals; Arginine; Cell Line; Cells, Cultured; Dose-Response Relationship, Drug; Endothelium, Vascular; Guanidines; Humans; Macrophages; Mice; Muscle Relaxation; Muscle, Smooth, Vascular; Nitric Oxide; Nitric Oxide Synthase; Saphenous Vein; omega-N-Methylarginine
PubMed: 7515129
DOI: 10.1038/ki.1994.98 -
Biochimica Et Biophysica Acta Nov 2012Bladder cancer is one of the leading lethal cancers worldwide. With the high risk of recurrence for bladder cancer following the initial diagnoses, lifelong monitoring...
Bladder cancer is one of the leading lethal cancers worldwide. With the high risk of recurrence for bladder cancer following the initial diagnoses, lifelong monitoring of patients is necessary. The lack of adequate sensitivity and specificity of current noninvasive monitoring approaches including urine cytology, other urine tests, and imaging, underlines the importance of studies that focus on the detection of more reliable biomarkers for this cancer. The emerging area of metabolomics, which deals with the analysis of a large number of small molecules in a single step, promises immense potential for discovering metabolite markers for screening and monitoring treatment response and recurrence in patients with bladder cancer. Since naturally-occurring canine transitional cell carcinoma of the urinary bladder is very similar to human invasive bladder cancer, spontaneous canine transitional cell carcinoma has been applied as a relevant animal model of human invasive transitional cell carcinoma. In this study, we have focused on profiling the metabolites in urine from dogs with transitional cell carcinoma and healthy control dogs combining nuclear magnetic resonance spectroscopy and statistical analysis methods. (1)H NMR-based metabolite profiling analysis was shown to be an effective approach for differentiating samples from dogs with transitional cell carcinoma and healthy controls based on a partial least square-discriminant analysis of the NMR spectra. In addition, there were significant differences in the levels of six individual metabolites between samples from dogs with transitional cell carcinoma and the control group based on the Student's t-test. These metabolites were selected to build a separate partial least square-discriminant analysis model that was then used to test the classification accuracy. The result showed good classification between transitional cell carcinoma and control groups with the area under the receiver operating characteristic curve of 0.85. The sensitivity and specificity of the model were 86% and 78%, respectively. These results suggest that urine metabolic profiling may have potential for early detection of bladder cancer and of bladder cancer recurrence following treatment, and may enhance our understanding of the mechanisms involved.
Topics: 3-Hydroxybutyric Acid; Acetone; Animals; Biomarkers, Tumor; Carcinoma, Transitional Cell; Choline; Citric Acid; Dogs; Humans; Magnetic Resonance Spectroscopy; Methylguanidine; Urea; Urinary Bladder Neoplasms
PubMed: 22967815
DOI: 10.1016/j.bbadis.2012.08.001