LWT-FOOD SCIENCE AND TECHNOLOGY
·
2023
·
IF 6
Fang Wei,Liyong Luo,Liang Zeng
Camellia nanchuanica gained attention for having original tea tree characteristics and producing black tea with appealing sweetness . To better study the sweet taste of Camellia nanchuanica black tea, 30 kinds of Camellia nanchuanica black tea (NCBT) samples were classified into three types (high, middle and low sweetness) according to the differences in sweetness. A total of 844 metabolites were detected in NCBT; among them, there were 155 differential metabolites. Four differential metabolites (phloridzin, dulcitol, l -alanine, and sucrose) positively correlated with sweetness and showed higher VIP (variable importance for the projection) values (>1), which made main contributions to the sweetness of NCBT. Phloridzin and l -alanine might be the key sweet compounds of NCBT due to higher DoT (dose-over-threshold) values. Addition experiments further verified that phloridzin was the key sweet taste compound because phloridzin significantly increased the sweet taste of low sweetness samples. Notably, although NCBT24, 26, and 28 belonged to high sweetness samples, phloridzin content was lower. Based on the interactions of binary mixture, hyper-addition effects of phloridzin, dulcitol, l -alanine, and sucrose existed in NCBT24, 26 and 28.
研究领域:
食品科学
·
植物化学
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产品关联
DOI
高影响因子
CHEMOSPHERE
·
2019
·
IF 5.108
Boyin Yan,Zhiquan Liu,Rui Huang,Yongpeng Xu,Dongmei Liu,Wei Wang,Zhiwei Zhao,Fuyi Cui,Wenxin Shi
Cyanobacteria produce a series of secondary metabolites , one of which is beta- N -methylamino- l -alanine (BMAA). BMAA is considered to be the cause of human neurodegeneration. Compared with other cyanotoxins, the role of BMAA in cyanobacteria remains unclear. To investigate this question, six strains of cyanobacteria were cultured and tested in this experiment with an optimized and validated BMAA determination method. The results show that four strains can produce BMAA. The effects of nutrient levels on the production of BMAA by Anabaena sp. FACHB-418 were studied by changing the initial concentrations of nitrate (NaNO 3 ) and phosphate (K 2 HPO 4 ) in mediums. Bound BMAA was detected in all samples and the concentrations were within 50–100 ng/g. Free BMAA was presence when the concentration of nitrogen was lower than 1.7 mg/L (121.43 μM). Free BMAA was released from the dead and ruptured cells during the cell decline period, so dissolved BMAA cannot be detectable in the adaptation and logarithmic periods, but could be abundant in the decline periods. Statistical analyses show that free BMAA concentrations were negatively correlated with nitrogen strongly (p = 2.334 × 10 −10 and r = −0.842), but positively correlated with phosphorus weakly (p = 0.016 and r = 0.405). Moreover, the results of culture experiments indicated that exogenous BMAA could inhibit the growth of cyanobacteria that cannot produce BMAA, and the effect was enhanced as the concentration of exogenous BMAA increased. This phenomenon implies that the production of BMAA may be the stress response by some cyanobacteria to low nitrogen conditions to kill other cyanobacteria, i.e., their competitors.
研究领域:
环境科学
·
毒理学
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产品关联
DOI
PubMed
高影响因子
BIOELECTROCHEMISTRY
·
2025
·
IF 4.5
Tingting Tian,Lixia Chen,Taiguang Li,Xiang Wang,Sen Yang,Huiqun Wang,Yujie Jiang,Xin Yao,Hong Zhao,Dengchao Wang,Xiangjun Li
Electrochemiluminescence (ECL) is highly recommended in chiral recognition. ECL-based chiral sensors highly desire a sensitive sensing interface for signal conversion and absolute chiral discrimination. The ECL emission based on a luminol-dissolved O 2 system received much attention due to its nontoxicity and stability. However, the drawback of weak ECL emission hinders the fast signal conversion from chiral discrimination to ECL response. Herein, the amplification strategy of ECL emission is proposed based on the electrochemical reduction enhanced O 2 reduction reaction (ORR). Cadmium sulfide decorated on carbon-nanotubes (CdS/CNTs) with easy synthesis, wide-pH operation, and suitable valence-conduction band position is employed. Upon cathodic scan, the electrons transfer from electrochemically reduced-CdS/CNTs to O 2 and H 2 O 2 , thus accelerating the generation of reactive oxide species (ROS) and furthering ECL emission. Furthermore, the chiral ECL sensing interface is well-designed by combining the chiral recognition of D-amino acid oxidase (DAAO) with the signal transduction and amplification of CdS/CNTs-enhanced ECL emission. During DAAO-catalyzed enantioselective-oxidations of alanine, the O 2 is converted to H 2 O 2 , which tunes the ROS generation. With synergetic regulations of ROS generation by nano-derived CdS/CNTs and bio-derived DAAO, alanine enantiomers are highly discriminated and the L-alanine is quantitatively detected with the most competitive detection limit so far (0.014 fM).
研究领域:
分析化学
·
生物化学
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产品关联
DOI
PubMed
高影响因子
International Journal of Electrochemical Science
·
2023
·
IF 1.5
Baoyang Lu,Yao Lu,Yangping Wen,Xuemin Duan,Jingkun Xu,Shuai Chen,Long Zhang
A novel chiral L-alanine-modified 3,4-ethylenedioxythiophene (EDOT) precursor, (2S)-(2,3-dihydrothieno[3,4- b ][1,4]dioxin-2-yl)methyl 2-( tert -butoxy carbonylamino)propanoate (EDOT-Boc-Ala), was synthesized and electropolymerized in CH 2 Cl 2 –Bu 4 NBF. The corresponding polymer, poly((2S)-(2,3-dihydrothieno[3,4- b ][1,4]dioxin-2-yl)methyl 2-( tert -butoxy carbonylamino)propanoate) (PEDOT-Boc-Ala) film showed good redox activity and stability. The electrochemical behavior, structural characterization, chirality, solubility, spectroscopic properties, thermal stability, and morphology of PEDOT-Boc-Ala film were investigated. Both doped and dedoped PEDOT-Boc-Ala film could well dissolve in strong polar solvents such as dimethyl sulfoxide, tetrahydrofuran, and acetone, etc. The determination of specific rotation showed that the electropolymerization of EDOT-Boc-Ala did not influence its conformation and the polymer exhibited an enhanced specific rotation ([α] 20.0 = -191.08°) in comparison with that of the monomer ([α] 20.0 = -30.77°). Moreover, the amperometric biosensor based on PEDOT-Boc-Ala film (as immobilization matrix of biologically-active species) was successfully fabricated and employed to determine the concentration of vitamin C.
研究领域:
材料科学
·
分析化学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Clinical and Experimental Pathology
·
2015
·
IF 1.891
Qingwei Zhang,Haiya Wu,Congcong Wen,Fa Sun,Xuezhi Yang,Lufeng Hu
MGCD0103, an isotype-selective HDACi, has been clinically evaluated for the treatment of hematologic malignancies and advanced solid tumors, alone and in combination with standard-of-care agents. In this study, we developed a serum metabolomic method based on gas chromatography-mass spectrometry (GC-MS) to evaluate the effect of intragastric administration of MGCD0103 on rats. The MGCD0103 group rats were given 20, 40, 80 mg/kg of MGCD0103 by intragastric administration each day for 7 days. Pattern recognition analysis, including both principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA) revealed that intragastric administration of MGCD0103 induced metabolic perturbations. As compared to the control group, the levels of L-alanine, L-isoleucine, and L-leucine of MGCD0103 group decreased. The results indicate that metabolomic methods based on GC-MS may be useful to elucidate side effect of MGCD0103 through the exploration of biomarkers (L-alanine, L-isoleucine, and L-leucine). According to the pathological changes of liver at difference dosage, MGCD0103 is hepatotoxic and its toxity is dose-dependent.
研究领域:
药理学
·
代谢组学
·
毒理学
✓ 已验证
DOI
PubMed
高影响因子
FOOD CHEMISTRY
·
2022
·
IF 9.231
Meng Wang,Jingjing Wang,Kangkang Wang,Liugen Zhang,Xianglei Cao,Cheng Guo,Jide Wang,Bin Wu
More and more attention has been paid to the improved QuEChERS (quick, easy, cheap, effective, rugged and safe) method in dealing complex sample matrices, especially for the study of QuEChERS adsorbents. In this study, a magnetic mesoporous material, which was derived from MIL-88B modified by l -alanine, was synthesized as modified QuEChERS adsorbents for the simultaneous determination of multiple pesticides (Methomyl, Isoprocarb, Carbofuran, 3-Hydroxycarbofuran, Acetamiprid, Imidacloprid) in Chinese cabbage, celery, long bean and leek. The prepared magnetic adsorbents can effectively remove interfering substances from the sample, and the proposed modified QuEChERS method can reduce sample pretreatment time via an external magnetic field. To achieve the best performance of QuEChERS method, the clean-up time and amount of QuEChERS adsorbents were investigated. Under the optimized conditions, a simple, rapid and sensitive method for the determination of 6 pesticide residues in vegetables was established by coupling the modified QuEChERS to ultrahigh-performance liquid chromatography-tandem mass spectrometry. Excellent sensitivity (The limit of detection for the 6 pesticides ranged from 0.001 to 0.020 µg kg −1 ), satisfactory linearity (r 2 ≥ 0.9952), good recovery (73.9–107.7%) and good precision (3.6–16.9% for intraday relative standard deviation, 0.5–15.0% for interday relative standard deviation) were obtained. Compared with traditional QuEChERS method, the proposed method is simple, cost-effective, and efficient, which indicates that the method can be used to detect carbamate and neonicotinoid pesticides in real samples and provide an excellent pretreatment technique for the detection of trace multi-analytes from complex substrates.
研究领域:
分析化学
·
食品安全
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 45
·38957-38963
·
IF 3.289
Zhao Cui,Ru Cheng,Jie Liu,Youping Wu,Jianping Deng
Poly(N-acryloyl-alanine)-based hydrophobic association hydrogels were prepared through free radical polymerization of N-acryloyl-alanine (NAA) with ammonium persulfate as initiator, in which hydrophobic monomer stearyl acrylate underwent simultaneous micellar polymerization in the presence of gelatin as emulsifier. Fourier transform infrared spectra and scanning electron microscopy demonstrated the formation and microscopic structure of the resulting hydrogels. The hydrophobic association enabled the hydrogels to exhibit desirable toughness and could be molded into diverse shapes without breaking. Uniaxial tensile test and cyclic tensile test also demonstrated the high toughness of the hydrogels. The chiral monomer (NAA)-derived polymer chains rendered the hydrogels with optical activity, according to circular dichroism spectra. More fascinatingly, the hydrogels demonstrated shape memory behavior due to the hydrophobic poly(stearyl acrylate) domains. Therefore the tough chiral hydrogels are expected to find significant applications in tissue engineering and other biomedical fields.
研究领域:
材料科学
·
生物医学工程
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Xiaoxiang Hu,Yajun Bai,Tai-Ping Fan,Xiaohui Zheng,Yujie Cai
A novel alanine dehydrogenase (ADH; EC.1.4.1.1) with high pyruvate reduced activity was isolated from Helicobacter aurati and expressed in Escherichia coli BL21 (DE3). The optimum pH of the reduction and oxidation reaction were 8.0 and 9.0, respectively, and the optimum temperature was 55 °C. With pyruvate and alanine as substrates, the specific activity of HAADH1 were 268 U·mg −1 and 26 U·mg −1 , respectively. HAADH1 had a prominent substrate specificity for alanine ( K m = 2.23 mM, k cat / K m = 8.1 s −1 ·mM −1 ). In the reduction reaction, HAADH1 showed the highest substrate affinity for pyruvate ( K m = 0.56 mM, k cat / K m = 364 s −1 ·mM −1 ). Compared to pyruvate, oxaloacetic acid, 2-ketobutyric acid, 3-fluoropyruvate, α-ketoglutaric acids, glyoxylic acid showed a residual activity of 93.30%, 8.93%, 5.62%, 2.57%, 2.51%, respectively. Phylogenetic tree analysis showed that this is a new type of ADH which have a low sequence similarity to available ADH reported in references. 3-Fluoropyruvate was effectively reduced to 3-fluoro-L-alanine by whole-cell catalysis.
研究领域:
生物化学
·
微生物学
·
酶学
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产品关联
DOI
PubMed
高影响因子
Systems Microbiology and Biomanufacturing
·
2024
·
IF 0
Huang Yu,Li Hedan,Zhao Guihong,Hu Xiaoqing,Wang Xiaoyuan
The production of L-alanine was enhanced in Corynebacterium glutamicum ATCC13869 through metabolic engineering of the biosynthesis pathways of L-alanine and fatty acids. Strains Δ fasB , Δ fasBR , Δ fasB Δ pks13 and Δ fasBR Δ pks13 were constructed and exhibited increased L-alanine yields up to 17.29 g/L. Different from Δ fasB mutant constructed from C. glutamicum ATCC13032 in which L-glutamate production accumulated, the muatnt Δ fasB constructed from C. glutamicum ATCC13869 in this study significantly produce L-alanine without L-glutamate accumulation. Transcriptional level analysis revealed that the knockout of fasB upregulated the expression levels of the genes related to L-alanine synthesis but downregulated those associated with fatty acid synthesis, confirming the redirection of metabolic flux from fatty acid synthesis to L-alanine synthesis in these strains. L-alanine productions were further enhanced in strains Δ fasB and Δ fasBR through the combinatorial expression of heterologous genes Bacillus subtilis alaD encoding alanine dehydrogenase and Escherichia coli alaE encoding alanine export protein, and the yields reached 55.21 g/L and 54.95 g/L, respectively. Finally, 69.9 g/L L-alanine was obtained in Δ fasB /pJYW-5- alaDE after 60 h of fermentation by supplementing glucose. Our data indicate that disrupting the fatty acid biosynthesis could redirect metabolic flux towards L-alanine biosynthesis. These results provide a new strategy for increasing the production of L-alanine in C. glutamicum . Graphical Abstract
研究领域:
微生物学
·
生物工程
·
分子生物学
✓ 已验证
DOI
Soft Matter
·
2025
·
IF 2.8
Huimin Han,Qingjing Niu,Kongying Zhu,Xiaoyan Yuan,Lixia Ren
Amphiphilic copolymers are reported to show excellent ice control activity for their special interaction with ice and water. In this work, amphiphilic L-methionine sulfoxide and L-alanine copolymers (MSACPs) with different block ratios (PMeto48-b-PAlay), different molecular weights and random (P(Meto48-co-Ala20)) structures are prepared, respectively, to study the structure and ice control activity relationship. The ice control activity is well studied using ice nucleation, dynamic ice shaping (DIS) and ice recrystallization inhibition (IRI). The MSACPs are self-assembled into micelles of 11 to 80 nm in aqueous solution, which promotes the heterogeneous ice nucleation. Among block copolymers with different block ratios (PMeto48-b-PAlay) and molecular weights, PMeto48-b-PAla20 with an appropriate block ratio and molecular weight shows the highest nucleation temperature (−18.2 °C), and excellent DIS and best IRI (the mean largest grain size is 34%) activities. And, for the block copolymers with a similar block ratio to that of PMeto48-b-PAla20, the DIS and IRI are closely related to the molecular weight as the ice control property is enhanced at high molecular weight. Compared with PMeto48-b-PAla20, the corresponding random copolymer, P(Meto48-co-Ala20), shows weaker ice control activity. Meanwhile, low-field nuclear magnetic resonance results show that the polymer–water interaction increases with hydrophobic block ratio, but has less effect on the molecular weight. The ice control activity is probably related to the balance between the polymer–water interaction and the polymer–ice interaction, and is optimized by both strong interactions.
研究领域:
生物化学
·
材料科学
·
低温生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FLUORESCENCE
·
2025
·
IF 3.1
Chen Xin,Wang Qing-wan,Zhan Tong-ling,Sun Yue,Zhang Xiao-rui,Liu Kun,Liu Xiao-wu
Nitrogen@Carbon quantum dots (N@CQDs) are prepared using microwave hydrothermal method, and polyvinylpyrrolidone (PVP) and melamine are used as mixed C source and N source. Microwave reaction conditions of preparing the N@CQDs are 170 ℃ and 3 h. This N@CQDs are are used as fluorescence probe for detection of amino acids. The N@CQDs can recognize L-alanine in water solution, and simultaneously recognize both L-methionine and L-cysteine in dimethyl sulfoxide (DMSO) solution. The linear ranges for L-alanine, L-methionine and L-cysteine are 0–15 µM, 2–50 µM and 0–17 µM, respectively. While limits of detection (LOD) for them are 11.092 nM, 7.8067 nM and 0.67476 nM, respectively. Compared to presently available detection methods, as-prepared N@CQDs have the advantage of high sensitivity and selectivity. Furthermore, coexistence of other amino acids has minimal interference in the detection of L-alanine, L-methionine and L-cysteine. For the as-prepared N@CQDs, solvent plays important roles in influencing the identification of amino acid types and detection sensitivity.
研究领域:
分析化学
·
生物传感
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Wenxiao Liu,Xuehua Deng,Yutong Dong,Sunting Xuan,Zhengbiao Zhang
The synthesis of N-substituted polypeptides is challenging due to steric hindrance. Here, N-alkyl poly(l-alanine)s, with controlled molecular weights (Mns) and narrow distributions, were efficiently synthesized by primary amine-initiated and acetic acid-catalyzed ring-opening polymerizations of N-alkyl-(l)-alanine N-carboxyanhydrides [NAlkyl-(l)-Ala-NCAs] in toluene of low polarity and low proton-accepting ability. The N-alkyl poly(l-alanine)s, with chiral centers at backbones and different alkyl substituents at side chains, showed a relatively extended helical structure similar to that of the PPII-helix of poly(l-proline). The elongation of the alkyl side chains and the increase in temperatures had negligible effects on the helix structure, as revealed by the circular dichroism measurements. The differential scanning calorimetry and X-ray diffraction measurements showed that the polymers were crystalline. Besides, the NAlkyl-(l)-Ala-NCAs were capable of copolymerizing with other monomers, producing structurally diverse copolymers. The efficient synthesis of N-alkyl poly(l-alanine)s, combined with the structural tunability, hydrophobicity, crystallinity, protein-like skeleton, enzymatic stability, and stable helix, makes the polymers attractive structural units in self-assembly and the biomedical field.
研究领域:
高分子化学
·
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）