Read by QxMD icon Read


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
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
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
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
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
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
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
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
Chao-Yu Yang, Ke Yu, Ye Wang, Song-An Chen, Dan-Dan Liu, Zheng-Yang Wang, Yan-Nan Su, Shao-Zhong Yang, Ting-Ting Chen, Itamar Livnat, Ferdinand S Vilim, Elizabeth C Cropper, Klaudiusz R Weiss, Jonathan V Sweedler, Jian Jing
One emerging principle is that neuromodulators, such as neuropeptides, regulate multiple behaviors, particularly motivated behaviors, e.g., feeding and locomotion. However, how neuromodulators act on multiple neural networks to exert their actions remains poorly understood. These actions depend on the chemical form of the peptide, e.g., an alternation of L- to D-form of an amino acid can endow the peptide with bioactivity, as is the case for the Aplysia peptide GdFFD (where dF indicates D-phenylalanine). GdFFD has been shown to act as an extrinsic neuromodulator in the feeding network, while the all L-amino acid form, GFFD, was not bioactive...
2016: PloS One
Joyanta K Modak, Wioletta Rut, Lakshmi C Wijeyewickrema, Robert N Pike, Marcin Drag, Anna Roujeinikova
The M17 aminopeptidase from the carcinogenic gastric bacterium Helicobacter pylori (HpM17AP) is an important housekeeping enzyme involved in catabolism of endogenous and exogenous peptides. It is implicated in H. pylori defence against the human innate immune response and in the mechanism of metronidazole resistance. Bestatin inhibits HpM17AP and suppresses H. pylori growth. To address the structural basis of catalysis and inhibition of this enzyme, we have established its specificity towards the N-terminal amino acid of peptide substrates and determined the crystal structures of HpM17AP and its complex with bestatin...
February 2016: Biochimie
Jichao Ma, Nengsheng Ye, Jian Li
In this work, a [Cu(mal)(bpy)]⋅H2O (mal, L-(-)-malic acid; bpy, 4,4'-bipyridyl) homochiral metal-organic frameworks (MOFs) was synthesized and used for modifying the inner walls of capillary columns by utilizing amido bonds to form covalent links between the MOFs particles and capillary inner wall. The synthesized [Cu(mal)(bpy)]⋅H2 O and MOFs-modified capillary column were characterized by X-ray diffraction, thermogravimetric analysis, particle size distribution analysis, nitrogen absorption characterization, FTIR spectroscopy, SEM, and energy-dispersive X-ray spectroscopy (EDX)...
February 2016: Electrophoresis
Shouji Takahashi, Kozue Shimada, Shunsuke Nozawa, Masaru Goto, Katsumasa Abe, Yoshio Kera
D-Aspartate oxidase (DDO) catalyzes the oxidative deamination of acidic D-amino acids, whereas neutral and basic D-amino acids are substrates of D-amino acid oxidase (DAO). DDO of the yeast Cryptococcus humicola (ChDDO) has much higher substrate specificity to D-aspartate, but the structural features that confer this specificity have not been elucidated. A three-dimensional model of ChDDO suggested that a histidine residue (His56) in the active site might be involved in the unique substrate specificity, possibly through the interaction with the substrate side chain in the active site...
March 2016: Journal of Biochemistry
Mr Sharad R Bobe, Mohammad Al Kobaisi, Sheshanath V Bhosale, Sidhanath V Bhosale
Protoporphyrin IX is a naturally occurring amphiphilic porphyrin with a rigid hydrophobic nonpolar core and two polar propionic acid substitutions on the porphyrin ring. This molecule can be modified on the hydrophilic group, which can lead to strengthened π-π-stacking and spontaneous self-assembly into novel nanostructures. Herein, we use l- phenylalanine and d-phenylalanine to modify protoporphyrin IX, and use the two derivatives for solvophobic-controlled self-assembly. Both derivatives possess two important features: 1) the aromatic core of the porphyrin for dispersive interactions and 2) a chiral amino acid to maximize the influence of chirality on selfassembly...
August 2015: ChemistryOpen
Luigi Longobardo, Marina DellaGreca, Ivan de Paola
Enantiopure N(Boc)-β(3)-amino nitriles, valuable synthetic intermediates in the multistep homologation of α-amino acids, were alkylated using n-BuLi as base. Alkylations afforded easily separable, almost equimolecular mixtures of diastereomeric N(Boc)-protected syn and anti β(2,3)-amino nitriles. Suitable manipulations of both cyano and amino groups eventually led to enantiopure N- and/or C-protected β(2,3)-amino acids. For example, methanolysis using conc. HCl gas in MeOH, provides C-protected β(2,3) amino acids in excellent yields...
2015: SpringerPlus
Shogo Nakano, Seiji Okazaki, Erika Ishitsubo, Nobuhiro Kawahara, Hidenobu Komeda, Hiroaki Tokiwa, Yasuhisa Asano
Alkaline D-peptidase from Bacillus cereus DF4-B, called ADP, is a D-stereospecific endopeptidase reacting with oligopeptides containing D-phenylalanine (D-Phe) at N-terminal penultimate residue. ADP has attracted increasing attention because it is useful as a catalyst for synthesis of D-Phe oligopeptides or, with the help of substrate mimetics, L-amino acid peptides and proteins. Structure and functional analysis of ADP is expected to elucidate molecular mechanism of ADP. In this study, the crystal structure of ADP (apo) form was determined at 2...
2015: Scientific Reports
Shengnan Zhang, Andrew P Hinck, Paul F Fitzpatrick
Liver phenylalanine hydroxylase is allosterically activated by phenylalanine. The structural changes that accompany activation have not been identified, but recent studies of the effects of phenylalanine on the isolated regulatory domain of the enzyme support a model in which phenylalanine binding promotes regulatory domain dimerization. Such a model predicts that compounds that stabilize the regulatory domain dimer will also activate the enzyme. Nuclear magnetic resonance spectroscopy and analytical ultracentrifugation were used to determine the ability of different amino acids and phenylalanine analogues to stabilize the regulatory domain dimer...
August 25, 2015: Biochemistry
Nishant Singh, Maria P Conte, R V Ulijn, Juan F Miravet, Beatriu Escuder
A low molecular weight hydrogelator with a covalently appended imidazole moiety is reported. Capable of percolating water in the pH range of 6 to 8, it proves to be an efficient catalyst upon self-assembly, showing Michaelis-Menten type kinetics. Activities at different pH values correlated with dramatic structural changes were observed. It can hydrolyse p-nitrophenyl acetate (pNPA) as well as inactivated esters, and L and D-phenylalanine methyl esters. The enhanced activity can be related to the conglomeration of catalytic groups upon aggregation resulting in their close proximity and the formation of hydrophobic pockets...
August 28, 2015: Chemical Communications: Chem Comm
Se-Yu Kim, Soo-Young Park, Soo-Keun Choi, Seung-Hwan Park
The development of diverse polymyxin derivatives is needed to solve the toxicity and resistance problems of polymyxins. However, no platform has generated polymyxin derivatives by genetically engineering a polymyxin synthetase, which is a nonribosomal peptide synthetase. In this study, we present a two-step approach for the construction of engineered polymyxin synthetases by substituting the adenylation (A) domains of polymyxin A synthetase, which is encoded by the pmxABCDE gene cluster of Paenibacillus polymyxa E681...
July 2015: Journal of Microbiology and Biotechnology
A Gholizadeh
Cysteine proteinases and their inhibitors 'cystatins' play essential roles in plant growth and development. They are involved in various signaling pathways and in the response to wide ranges of biotic and abiotic environmental stresses. To investigate their possible influence from D-amino acids or their metabolism in vivo, Arabidopsis seedlings were allowed to grow under four physicochemically different D-amino acids including D-aspartate, D-serine, D-alanine and D-phenylalanine containing media. The reverse transcription polymerase chain reaction (R T-PCR) analysis of cysteine proteinase and cystatin gene expressions showed that the addition of D-amino acid to the plant growth media considerably induce the expression of proteinase transcript while decrease the expression level of inhibitor gene in the leaf and root tissues of the test plant in overall...
March 2015: T︠S︡itologii︠a︡ i Genetika
Fabio Parmeggiani, Sarah L Lovelock, Nicholas J Weise, Syed T Ahmed, Nicholas J Turner
The synthesis of substituted D-phenylalanines in high yield and excellent optical purity, starting from inexpensive cinnamic acids, has been achieved with a novel one-pot approach by coupling phenylalanine ammonia lyase (PAL) amination with a chemoenzymatic deracemization (based on stereoselective oxidation and nonselective reduction). A simple high-throughput solid-phase screening method has also been developed to identify PALs with higher rates of formation of non-natural D-phenylalanines. The best variants were exploited in the chemoenzymatic cascade, thus increasing the yield and ee value of the D-configured product...
April 7, 2015: Angewandte Chemie
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"