25191-15-5Relevant articles and documents
Oxepine-containing diketopiperazine alkaloids from the algal-derived endophytic fungus paecilomyces variotii EN-291
Zhang, Peng,Li, Xiao-Ming,Wang, Jia-Ning,Wang, Bin-Gui
, p. 800 - 804 (2015)
Two new oxepine-containing diketopiperazine-type alkaloids, varioloids A and B (1 and 2, resp.), were isolated from the algal-derived fungus Paecilomyces variotii EN-291. The structures and absolute configurations were determined by detailed interpretation of 1D- and 2D-NMR spectroscopic data and by analysis of acidic hydrolysates. Compounds 1 and 2 exhibited potent activity against the plant-pathogenic fungus Fusarium graminearum with MIC values of 8 and 4 μg/ml, respectively.
Characterization of D-aminoacylase from Alcaligenes denitrificans DA181.
Yang,Hsiao,Li,Yano,Tsugita,Tsai
, p. 1392 - 1395 (1992)
The D-aminoacylase produced by Alcaligenes denitrificans DA181 was a new type of aminoacylase which had both high stereospecificity and specific activity. The molecular weight and isoelectric point of this enzyme were 58,000 and 4.4, respectively. The apparent Km and kcat values of this enzyme for N-acetyl-D-methionine were estimated to be 0.48 mM and 6.24 x 10(4) min-1, respectively. The optimum temperature was 45 degrees C. The enzyme was stable up to 55 degrees C for 1 hr in the presence of 0.2 mg/ml bovine serum albumin. The enzyme was stable in the pH range of 6.0 to 11.0 with an optimum pH of 7.5. This enzyme contained about 2.1 g atom of zinc per mole of enzyme. Enzyme activity was inhibited by incubation with EDTA. The inhibition by EDTA was fully reversed by Co2+ and partially by Zn2+.
Extraction of phenylalanine enantiomers by aqueous two phase systems containing combinatorial chiral selector
Chen, Xiaoqing,Liu, Li,Jiao, Feipeng,Wang, Zhen
, p. 965 - 969 (2012)
In order to obtain a better enantioselectivity of phenylalanine enantiomers and establish the optimal chiral extraction conditions, the distribution behavior was investigated in aqueous two-phase systems which were composed of polyethylene glycol and ammonium sulfate containing combinatorial chiral selector: β-cyclodextrin and HP-β-cyclodextrin. The influence of the molar concentration ratio of combinatorial chiral selectors, the total molar concentration of combinatorial chiral selectors, pH value, buffer type and its concentration were thoroughly studied, respectively. The results show that the enantioselectivity reaches 1.53 under the optimal chiral extraction conditions. This extraction is a potential economical and effective way for chiral resolution. Copyright
Biphasic Enantioselective Fluorescent Recognition of Amino Acids by a Fluorophilic Probe
Zhu, Yuan-Yuan,Wu, Xue-Dan,Abed, Mehdi,Gu, Shuang-Xi,Pu, Lin
, p. 7866 - 7873 (2019)
A fluorophilic fluorescent probe based on a perfluoroalkyl-substituted bis(binaphthyl) compound was designed and synthesized. It displayed a highly enantioselective fluorescence response toward structurally diverse amino acids in a biphasic fluorous/aqueous system with enantiomeric fluorescent enhancement ratio (ef; ΔID/ΔIL) values up to 45.2 (histidine). It can be used to determine the enantiomeric compositions of amino acids and also allows the amino acid enantiomers to be visually discriminated. NMR and mass-spectroscopic investigations provided insights into the observed high enantioselectivity. This biphasic fluorescent recognition was used to determine the enantiomeric composition of the crude phenylalanine products generated by an enzyme-catalyzed asymmetric hydrolysis under various reaction conditions. The fluorous-phase-based fluorescence measurement under the biphasic conditions was able to minimize the interference of other reaction components and thus has potential in asymmetric reaction screening.
Challenges in the assignment of relative and absolute configurations of complex molecules: Computation can resolve conflicts between theory and experiment
Ren, Jie,Li, Guo-You,Shen, Lan,Zhang, Guo-Lin,Nafie, Laurance A.,Zhu, Hua-Jie
, p. 10351 - 10356 (2013)
The configuration of (-)-brevianamides was assigned as (2S,13S) based on X-ray structure analysis and hydrolysis experiments. However, our theoretical investigation of its chiroptical properties strongly implied that the correct configuration should be (2R,13R). The reasons for the incorrect earlier assignment are analyzed by calculations of conversion energy barriers among different intermediates, starting materials and final products. This study demonstrates that conflicting theoretical and, experimental results suggest that it is premature to assign the configuration of a natural product.
Molecularly imprinted polymer as stationary phase for HPLC separation of phenylalanine enantiomers
Hroboňová, Katarína,Lomenova, Anna
, p. 939 - 946 (2018)
Abstract: l-Phenylalanine molecularly imprinted polymers were synthesized by bulk polymerization. Methacrylic acid and acrylamide were tested as functional monomers. Ethanol and acetonitrile were used as porogenic solvents. Optimal composition of polymerization mixture was methacrylic acid, template, and ethylene glycol dimethacrylate in molar ratio 1:5:26. MIP was applied as HPLC chiral stationary phase. The influences of the mobile phase composition, flow rate, column temperature, and column length on the efficiency of enantioseparation were investigated. The enantioselective separation of phenylalanine was attained in reversed phase mode at 45?°C with acetonitrile/water containing 1.5% acetic acid (90/10, v/v) as mobile phase (resolution value was 1.49, selectivity factor was 1.38). Applicability of polymeric stationary phase prepared for l-phenylalanine was tested for analysis of dietary supplement sample. The UV detection limits for both enantiomers were 1?mg?cm?3 (S/N?=?3). Good linearity was observed from 1 to 10?mg?cm?3.
Enantioselective liquid-liquid extractions of underivatized general amino acids with a chiral ketone extractant
Huang, Haofei,Nandhakumar, Raju,Choi, Misun,Su, Zhishan,Kim, Kwan Mook
, p. 2653 - 2658 (2013)
The chiral ketone (S)-3 shows high kinetic enantioselectivities toward the l form for general underivatized amino acids with hydrophobic side chains and a high thermodynamic enantioselectivity toward the d form for cysteine with its -SH polar side chain when used as an extractant in enantioselective liquid-liquid extractions in the presence of Aliquat 336. Consecutive extractions by imine formation and hydrolysis increase the enantiopurity of the amino acid, as both of these reactions are l-form-selective.
Noncovalent chirality sensing ensembles for the detection and reaction monitoring of amino acids, peptides, proteins, and aromatic drugs
Biedermann, Frank,Nau, Werner M.
, p. 5694 - 5699 (2014)
Ternary complexes between the macrocyclic host cucurbit[8]uril, dicationic dyes, and chiral aromatic analytes afford strong induced circular dichroism (ICD) signals in the near-UV and visible regions. This allows for chirality sensing and peptide-sequence recognition in water at low micromolar analyte concentrations. The reversible and noncovalent mode of binding ensures an immediate response to concentration changes, which allows the real-time monitoring of chemical reactions. The introduced supramolecular method is likely to find applications in bioanalytical chemistry, especially enzyme assays, for drug-related analytical applications, and for continuous monitoring of enantioselective reactions, particularly asymmetric catalysis. Strong and diagnostic induced circular dichroism signals in the near-UV or visible region are obtained when chiral, optically transparent analytes bind to an achiral chemosensing ensemble composed of a macrocyclic host and dye. This affords a novel, supramolecular detection method for chiral aromatic analytes in water.
Enantiomeric separation of underivatized amino acids: Predictability of chiral recognition on ristocetin a chiral stationary phase
Wagdy, Hebatallah A.,Hanafi, Rasha S.,El-Nashar, Rasha M.,Aboul-Enein, Hassan Y.
, p. 132 - 135 (2014)
The present work aimed to investigate the predictability of the chromatographic behavior for the separation of underivatized amino acids on ristocetin A, known as Chirobiotic R, using a DryLab high-performance liquid chromatography (HPLC) method development software, which is typically used to predict the effect of changing various chromatographic parameters on resolution in the reversed phase mode. After implementing the basic runs, and judging the predictability via the computed resolution map, it can be deduced that the chiral recognition mechanisms tend towards a hydrophilic interaction chromatography rather than the reversed phase mode, which limits the ability of DryLab software to predict separations on Chirobiotic R.
Varioxepine a, a 3H-oxepine-containing alkaloid with a new oxa-cage from the marine algal-derived endophytic fungus Paecilomyces variotii
Zhang, Peng,Mandi, Attila,Li, Xiao-Ming,Du, Feng-Yu,Wang, Jia-Ning,Li, Xin,Kurtan, Tibor,Wang, Bin-Gui
, p. 4834 - 4837 (2014)
A new 3H-oxepine-containing alkaloid, varioxepine A (1), characterized by a structurally unprecedented condensed 3, 6, 8-trioxabicyclo[3.2.1]octane motif, was isolated from the marine algal-derived endophytic fungus Paecilomyces variotii. Due to the low proton/carbon ratio, the unambiguous assignment of the planar structure and relative configuration was precluded by NMR experiments and solved by single crystal X-ray analysis. The absolute configuration was established by DFT conformational analysis and TDDFT-ECD calculations. Compound 1 inhibited plant pathogenic fungus Fusarium graminearum.
