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https://www.readbyqxmd.com/read/29131418/stereoselective-nanozyme-based-on-ceria-nanoparticles-engineered-with-amino-acids
#1
Xiaogang Qu, Yuhuan Sun, Chuanqi Zhao, Nan Gao, Jinsong Ren
Stereoselectivity towards substrate is one of the most important characteristics of enzymes. Amino acids, as cofactors of many enzymes, play important roles in stereochemistry. Herein, chiral nanozymes were constructed by grafting a series of D- or L-amino acids on surfaces of ceria (cerium oxide) nanoparticles. We selected the most commonly used drug for combating Parkinson's disease 3, 4-dihydroxyphenylalanine (DOPA) enantiomers as examples for chiral catalysis. Through detailed kinetic studies of eight amino acids modified cerium oxide nanoparticles (CeNP), we found that phenylalanine-modified CeNP was optimal for the DOPA oxidation reaction and showed excellent stereoselectivity towards its enantiomers...
November 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29035420/modeling-the-secondary-structures-of-the-peptaibols-antiamoebin-i-and-zervamicin-ii-modified-with-d-amino-acids-and-proline-analogues
#2
Tarsila G Castro, Nuno M Micaêlo, Manuel Melle-Franco
Antiamoebin I (AAM-I) and zervamicin II (Zrv-IIB) are peptaibols that exert antibiotic activity through the insertion/disruption of cell membranes. In this study, we investigated how the folding of these peptaibols are affected when some of their native residues are replaced with proline analogues and asymmetrical D-α,α-dialkyl glycines (two classes of noncanonical amino acids). Systematic substitutions of native Aib, Pro, Hyp, and Iva residues were performed to elucidate the folding properties of the modified peptaibols incorporating noncanonical residues...
October 16, 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28861053/enhanced-biocide-treatments-with-d-amino-acid-mixtures-against-a-biofilm-consortium-from-a-water-cooling-tower
#3
Ru Jia, Yingchao Li, Hussain H Al-Mahamedh, Tingyue Gu
Different species of microbes form mixed-culture biofilms in cooling water systems. They cause microbiologically influenced corrosion (MIC) and biofouling, leading to increased operational and maintenance costs. In this work, two D-amino acid mixtures were found to enhance two non-oxidizing biocides [tetrakis hydroxymethyl phosphonium sulfate (THPS) and NALCO 7330 (isothiazoline derivatives)] and one oxidizing biocide [bleach (NaClO)] against a biofilm consortium from a water cooling tower in lab tests. Fifty ppm (w/w) of an equimass mixture of D-methionine, D-leucine, D-tyrosine, D-tryptophan, D-serine, D-threonine, D-phenylalanine, and D-valine (D8) enhanced 15 ppm THPS and 15 ppm NALCO 7330 with similar efficacies achieved by the 30 ppm THPS alone treatment and the 30 ppm NALCO 7330 alone treatment, respectively in the single-batch 3-h biofilm removal test...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28718982/design-and-solution-phase-synthesis-of-membrane-targeting-lipopeptides-with-selective-antibacterial-activity
#4
Mohini M Konai, Utsarga Adhikary, Jayanta Haldar
Designing selective antibacterial molecules remains an unmet goal in the field of membrane-targeting agents. Herein, we report the rational design and synthesis of a new class of lipopeptides, which possess highly selective bacterial killing over mammalian cells. The selective interaction with bacterial over mammalian membranes was established through various spectroscopic, as well as microscopic experiments, including biophysical studies with the model membranes. A detailed antibacterial structure-activity relationship was delineated after preparing a series of molecules consisting of the peptide moieties with varied sequence of amino acids, such as d-phenylalanine, d-leucine, and d-lysine...
July 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28715084/synthesis-of-cupf6-s-binap-loaded-resin-and-its-enantioselectivity-toward-phenylalanine-enantiomers
#5
Xiong Liu, Wenqi Zhou, Longqi Xu
A type of resin-anchored CuPF6 -(S)-BINAP was synthesized and identified. The PS-CuPF6 -(S)-BINAP resin was used to adsorb the phenylalanine enantiomers. The results showed that the adsorption capacity of PS-CuPF6 -(S)-BINAP resin toward L-phenylalanine was higher than that of resin toward D-phenylalanine. PS-CuPF6 -(S)-BINAP resin exhibited good enantioselectivity toward L-phenylalanine and D-phenylalanine. The influence of phenylalanine concentration, pH, adsorption time, and temperature on the enantioselectivity of the resin were investigated...
September 2017: Chirality
https://www.readbyqxmd.com/read/28606509/targeting-integrin-rich-tumors-with-temoporfin-loaded-vitamin-e-succinate-grafted-chitosan-oligosaccharide-d-%C3%AE-tocopheryl-polyethylene-glycol-1000-succinate-nanoparticles-to-enhance-photodynamic-therapy-efficiency
#6
Junru Wu, Shu Feng, Wenchao Liu, Feng Gao, Yanzuo Chen
A major challenge in cancer photodynamic therapy (PDT) is the poor tumor selectivity of the photosensitizer. Therefore, temoporfin (mTHPC)-loaded nanoparticles, based on vitamin-E-succinate-grafted chitosan oligosaccharide and cyclic (arginine-glycine-aspartic acid-d-phenylalanine-lysine) (c[RGDfK])-modified d-α-tocopheryl polyethylene glycol 1000 succinate, were prepared (RGD-NPs) and were expected to enhance the accumulation of mTHPC in integrin-rich U87MG tumors. The RGD-NPs generated were 144.9nm in diameter and uniformly spherical...
August 7, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28551019/determination-of-the-stereoisomeric-impurities-of-sitafloxacin-by-capillary-electrophoresis-with-dual-chiral-additives
#7
Ranran Meng, Jingwu Kang
Because of the bioactivity against the human topoisomerase II, the stereoisomeric impurities of sitafloxacin should be controlled in the process of manufactory. In the present work, a capillary electrophoresis (CE) method was developed and validated for simultaneous determination of three stereoisomeric impurities of sitafloxacin. The separation with high resolution not only for the separation of enantiomers, but also for the separation of diastereoisomers was achieved by using a background electrolyte composed of dual chiral selectors, namely γ-cyclodextrin (γ-CD) and Cu(2+)-d-phenylalanine (D-Phe) complex...
July 14, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28493432/phenol-metabolism-and-preservation-of-fresh-in-hull-walnut-stored-in-modified-atmosphere-packaging
#8
Jin Wang, Pan Li, Bi Gong, Shuying Li, Huiling Ma
BACKGROUND: The effects of modified atmosphere packaging (MAP) on phenol metabolism and preservation of fresh in-hull walnuts have been investigated. Fruit was packaged under MAP1 (film thickness, 30 μm), MAP2 (45 μm) and MAP3 (50 μm) and stored at -0.5 to 1.0 °C for up to 60 days. RESULTS: Firmness, soluble solid concentration, total phenols, total flavonoids and total antioxidant activity of the green hull were maintained at higher levels under the MAP conditions, whereas decay incidence was lower compared to the control during storage...
May 11, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/28395254/facile-and-efficient-electrochemical-enantiomer-recognition-of-phenylalanine-using-%C3%AE-cyclodextrin-immobilized-on-reduced-graphene-oxide
#9
Shabi Abbas Zaidi
This work demonstrates the facile and efficient preparation protocol of β-Cyclodextrin-reduced graphene oxide modified glassy carbon electrode (β-CD/RGO/GCE) sensor for an impressive chiral selectivity analysis for phenylalanine enantiomers. In this work, the immobilization of β-CD over graphene sheets allows the excellent enantiomer recognition due to the large surface area and high conductivity of graphene sheets and extraordinary supramolecular (host-guest interaction) property of β-CD. The proposed sensor was well characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) techniques...
April 5, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28363957/structure-based-engineering-of-an-artificially-generated-nadp-dependent-d-amino-acid-dehydrogenase
#10
Junji Hayashi, Tomonari Seto, Hironaga Akita, Masahiro Watanabe, Tamotsu Hoshino, Kazunari Yoneda, Toshihisa Ohshima, Haruhiko Sakuraba
A stable NADP(+)-dependent d-amino acid dehydrogenase (DAADH) was recently created from Ureibacillus thermosphaericusmeso-diaminopimelate dehydrogenase through site-directed mutagenesis. To produce a novel DAADH mutant with different substrate specificity, the crystal structure of apo-DAADH was determined at a resolution of 1.78 Å, and the amino acid residues responsible for the substrate specificity were evaluated using additional site-directed mutagenesis. By introducing a single D94A mutation, the enzyme's substrate specificity was dramatically altered; the mutant utilized d-phenylalanine as the most preferable substrate for oxidative deamination and had a specific activity of 5...
June 1, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28292014/ameliorative-effect-of-chromium-d-phenylalanine-complex-on-indomethacin-induced-inflammatory-bowel-disease-in-rats
#11
S Nagarjun, Shivsharan B Dhadde, Veeresh P Veerapur, B S Thippeswamy, Baburao N Chandakavathe
Present study was designed to evaluate the effect of chromium-d-phenylalanine complex (Cr (d-phe)3) on indomethacin-induced inflammatory bowel disease (IBD) in rats. Adult Wistar rats were pretreated with vehicle/Cr (d-phe)3 (30, 60 and 90μg/kg, p.o.) for 11days. On day 8 and 9, after one h of the above mentioned treatment, indomethacin (7.5mg/kg/day,s.c.) was administered to induce IBD. On day 12, blood samples were collected from animals for lactate dehydrogenase (LDH) estimation and ileum was isolated for macroscopic scoring, biochemical estimation (lipid peroxidation, reduced glutathione and myeloperoxidase activity) and histopathological study...
May 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28286213/carbonic-anhydrase-activation-enhances-object-recognition-memory-in-mice-through-phosphorylation-of-the-extracellular-signal-regulated-kinase-in-the-cortex-and-the-hippocampus
#12
Lucas Canto de Souza, Gustavo Provensi, Daniela Vullo, Fabrizio Carta, Andrea Scozzafava, Alessia Costa, Scheila Daiane Schmidt, Maria Beatrice Passani, Claudiu T Supuran, Patrizio Blandina
Rats injected with by d-phenylalanine, a carbonic anhydrase (CA) activator, enhanced spatial learning, whereas rats given acetazolamide, a CA inhibitor, exhibited impairments of fear memory consolidation. However, the related mechanisms are unclear. We investigated if CAs are involved in a non-spatial recognition memory task assessed using the object recognition test (ORT). Systemic administration of acetazolamide to male CD1 mice caused amnesia in the ORT and reduced CA activity in brain homogenates, while treatment with d-phenylalanine enhanced memory and increased CA activity...
May 15, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/27795612/polarized-raman-spectroscopy-for-determining-the-orientation-of-di-d-phenylalanine-molecules-in-a-nanotube
#13
Valentin Sereda, Nicole M Ralbovsky, Milana C Vasudev, Rajesh R Naik, Igor K Lednev
Self-assembly of short peptides into nanostructures has become an important strategy for the bottom-up fabrication of nanomaterials. Significant interest to such peptide-based building blocks is due to the opportunity to control the structure and properties of well-structured nanotubes, nanofibrils, and hydrogels. X-ray crystallography and solution NMR, two major tools of structural biology, have significant limitations when applied to peptide nanotubes because of their non-crystalline structure and large weight...
September 2016: Journal of Raman Spectroscopy: JRS
https://www.readbyqxmd.com/read/27664053/d-phenylalanine-inhibits-biofilm-development-of-a-marine-microbe-pseudoalteromonas-sp-sc2014
#14
Ee Li, Jiajia Wu, Peng Wang, Dun Zhang
D-amino acids have been reported to be able to inhibit biofilm formation or disperse existing biofilms of many microbes, in some cases, it is due to growth inhibition as an unspecific effect. In this work, six different D-amino acids were tested for their inhibitory effects on biofilm development and bacteria growth of Pseudoalteromonas sp. SC2014, a marine microbe involving in microbiologically influenced corrosion (MIC). Experimental results indicated that D-phenylalanine (D-Phe) inhibited biofilm formation effectively at concentrations that did not affect cell growth, whereas, the other D-amino acids either showed little effect or inhibited biofilm formation when inhibited bacteria growth...
September 22, 2016: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/27617997/synthesis-and-cytotoxic-activity-on-human-cancer-cells-of-novel-isoquinolinequinone-amino-acid-derivatives
#15
Jaime A Valderrama, Virginia Delgado, Sandra Sepúlveda, Julio Benites, Cristina Theoduloz, Pedro Buc Calderon, Giulio G Muccioli
A variety of aminoisoquinoline-5,8-quinones bearing α-amino acids moieties were synthesized from 3-methyl-4-methoxycarbonylisoquinoline-5,8-quinone and diverse l- and d-α-amino acid methyl esters. The members of the series were evaluated for their cytotoxic activity against normal and cancer cell lines by using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay. From the current investigation, structure-activity relationships demonstrate that the location and structure of the amino acid fragment plays a significant role in the cytotoxic effects...
September 8, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27422518/genetics-of-amino-acid-taste-and-appetite
#16
REVIEW
Alexander A Bachmanov, Natalia P Bosak, John I Glendinning, Masashi Inoue, Xia Li, Satoshi Manita, Stuart A McCaughey, Yuko Murata, Danielle R Reed, Michael G Tordoff, Gary K Beauchamp
The consumption of amino acids by animals is controlled by both oral and postoral mechanisms. We used a genetic approach to investigate these mechanisms. Our studies have shown that inbred mouse strains differ in voluntary amino acid consumption, and these differences depend on sensory and nutritive properties of amino acids. Like humans, mice perceive some amino acids as having a sweet (sucrose-like) taste and others as having an umami (glutamate-like) taste. Mouse strain differences in the consumption of some sweet-tasting amino acids (d-phenylalanine, d-tryptophan, and l-proline) are associated with polymorphisms of a taste receptor, type 1, member 3 gene (Tas1r3), and involve differential peripheral taste responsiveness...
July 2016: Advances in Nutrition
https://www.readbyqxmd.com/read/27225330/synthesis-of-novel-chiral-sulfonamide-bearing-1-2-4-triazole-3-thione-analogs-derived-from-d-and-l-phenylalanine-esters-as-potential-anti-influenza-agents
#17
Eyüp Başaran, Ayşegül Karaküçük-Iyidoğan, Dominique Schols, Emine Elçin Oruç-Emre
Novel enantiopure 1,2,4-trizole-3-thiones containing a benzensulfonamide moiety were synthesized via multistep reaction sequence starting with D-phenylalanine methyl ester and L-phenylalanine ethyl ester as a source of chirality. The chemical structures of all compounds were characterized by elemental analysis, UV, IR, (1) H NMR, (13) C NMR, 2D NMR (HETCOR), and mass spectral data. All compounds were tested in vitro antiviral activity against a broad variety of DNA and RNA viruses and in vitro cytostatic activity against murine leukemia (L1210), human T-lymphocyte (CEM) and human cervix carcinoma (HeLa) cell lines...
June 2016: Chirality
https://www.readbyqxmd.com/read/27015640/development-of-an-hplc-method-with-an-ods-column-to-determine-low-levels-of-aspartame-diastereomers-in-aspartame
#18
Takashi Ohtsuki, Ryoichiro Nakamura, Satoru Kubo, Akira Otabe, Yoko Oobayashi, Shoko Suzuki, Mika Yoshida, Mitsuya Yoshida, Chiye Tatebe, Kyoko Sato, Hiroshi Akiyama
α-L-Aspartyl-D-phenylalanine methyl ester (L, D-APM) and α-D-aspartyl-L-phenylalanine methyl ester (D, L-APM) are diastereomers of aspartame (N-L-α-Aspartyl-L-phenylalanine-1-methyl ester, L, L-APM). The Joint FAO/WHO Expert Committee on Food Additives has set 0.04 wt% as the maximum permitted level of the sum of L, D-APM and D, L-APM in commercially available L, L-APM. In this study, we developed and validated a simple high-performance liquid chromatography (HPLC) method using an ODS column to determine L, D-APM and D, L-APM in L, L-APM...
2016: PloS One
https://www.readbyqxmd.com/read/26856689/conformational-transformation-of-ascidiacyclamide-analogues-induced-by-incorporating-enantiomers-of-phenylalanine-1-naphthylalanine-or-2-naphthylalanine
#19
Akiko Asano, Katsuhiko Minoura, Takeshi Yamada, Mitsunobu Doi
We designed five ascidiacyclamide analogues [cyclo(-Xxx(1) -oxazoline(2) -d-Val(3) -thiazole(4) -l-Ile(5) -oxazoline(6) -d-Val(7) -thiazole(8) -)] incorporating l-1-naphthylalanine (l-1Nal), l-2-naphthylalanine (l-2Nal), d-phenylalanine (d-Phe), d-1-naphthylalanine (d-1Nal) or d-2-naphthylalanine (d-2Nal) into the Xxx(1) position of the peptide. The conformations of these analogues were then examined using (1) H NMR, CD spectroscopy, and X-ray diffraction. These analyses suggested that d-enantiomer-incorporated ASCs [(d-Phe), (d-1Nal), and (d-2Nal)ASC] transformed from the folded to the open structure in solution more easily than l-enantiomer-incorporated ASCs [(l-Phe), (l-1Nal), and (l-2Nal)ASC]...
March 2016: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/26853976/enantioselective-assembly-of-amphipathic-chiral-polymer-and-racemic-chiral-small-molecules-during-preparation-of-micro-scale-polymer-vesicles
#20
Yingjue Wang, Yiwei Zhuang, Jiangang Gao, Gang Zou, Qijin Zhang
Enantioselective assembly is observed during preparation of vesicles from a solution mixture of an amphipathic block copolymer bearing pendent chiral L- or D-phenylalanine groups in hydrophobic segments and racemic chiral small molecules. Primary experimental results reveal that racemic chiral small molecules have been enantioselectively encapsulated into the hydrophobic shells of assembled vesicles with homochiral bilayer membrane structure, showing reverse CD signals compared with the original vesicles. A further study shows that the enantiomeric excess obtained through the enantioselective assembly is directly dependent on the molecular weight of the hydrophobic chiral chain segments, implying both the hydrophobic interaction and chirality are key points during the assembly of vesicles...
March 14, 2016: Soft Matter
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