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1.
Chemistry ; 2020 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-32145120

RESUMO

Nanoporous metals (NPMs) can be readily fabricated via chemical or electrochemical dealloying of monolithic alloys with diversified shapes and compositions. Benefited from their high surface area, high density of steps and kinks on the ligament surface, and unsupported character, NPMs have attracted increasing attentions as a new class of heterogeneous catalysts with high reactivity, selectivity and long-term stability. In the present minireview, we summarize the recent advances in this exciting field and provide a critical discussion of the nature of their active sites and the structure-property correlation.

2.
Int J Biol Macromol ; 148: 333-341, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31954783

RESUMO

Deacetyl-7-aminocephalosporanic acid (D-7-ACA) is required for producing of many semisynthetic ß-lactam antibiotics; therefore, enzymes capable of converting 7-aminocephalosporanic acid (7-ACA) to D-7-ACA present a valuable resource to the pharmaceutical industry. In the present study, a putative acetylesterase, EstZY, was identified and characterized from a thermophilic bacterium Alicyclobacillus tengchongensis. Sequence alignment showed that EstZY was an acetylesterase which belonged to carbohydrate esterase family 7 (CE7), with substrate preference for short-chain acyl esters p-NPC2 to p-NPC8. Maximum enzyme activity was recorded at pH 9.0 and 50 °C, where Km and Vmax were calculated as 1.9 ± 0.23 mM and 258 ± 18.5 µM min-1, respectively. The residues Ser185, Asp274, and His303 were identified as the putative catalytic triad by homology modelling, site-directed mutagenesis and molecular docking. Moreover, EstZY can remove the acetyl group at C3' position of 7-ACA to form D-7-ACA; this is the first report of a 7-ACA deacetylase from CE7 family in A. tengchongensis and may represent a new enzyme with industrial values.

3.
Sheng Wu Gong Cheng Xue Bao ; 35(2): 327-336, 2019 Feb 25.
Artigo em Chinês | MEDLINE | ID: mdl-30806063

RESUMO

Nowadays, available phosphorus (P) deficiency in soil and weed resistance to herbicides have emerged as two severe limiting factors for sustainable agriculture. Therefore, it is of urgent needs to improve plant absorption/utilization ability of the soil P, seek phosphate (Pi)-alternative P fertilizers, and develop new forms of weed control systems. Phosphite (Phi), as a P resource of relatively high amount only less than Pi in Earth, can be converted to utilizable Pi uniquely in some bacterial species by oxidization via its specific dehydrogenase (PTDH), but inhibits plant growth and development. This implies that Phi might rather become a suitable P fertilizer for plants if introducing a PTDH detoxifier from bacteria. Herein, we created the transgenic tobaccos harboring a Pseudomonas PTDH gene (PsPtx) amplified from the soil metagenome previously. RT-PCR showed that the exotic PsPtx gene could express similarly in root, stem and leaf tissues of all transgenic lines. PsPtx transgenic tobaccos could utilize Phi by oxidization as the sole Pi supply, and also outperformed wild-type tobacco with a remarkably dominant growth under Phi stress conditions. Moreover, the PsPtx gene was preliminarily evaluated with a notable quality as a potential candidate of the selection marker in plant genetic transformation. Conclusively, PsPtx and its encoded phosphite dehydrogenase might be applicable for developing a dual system of plant phosphorus utilization and weed control using Phi as P fertilizer and herbicide, and provide an effectual solution to some obstacles in the current crop transgenic studies.


Assuntos
Controle de Plantas Daninhas , Oxirredutases , Fosfitos , Fósforo , Plantas Geneticamente Modificadas
4.
Mol Membr Biol ; 33(3-5): 39-50, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-29025361

RESUMO

Membrane-bound pyrophosphatases (PPases) are involved in the adaption of organisms to stress conditions, which was substantiated by numerous plant transgenic studies with H+-PPase yet devoid of any correlated evidences for other two subfamilies, Na+-PPase and Na+,H+-PPase. Herein, we demonstrate the gene cloning and functional evaluation of the membrane-bound PPase (CmPP) of the human gut microbe Clostridium methylpentosum. The CmPP gene encodes a single polypeptide of 699 amino acids that was predicted as a multi-spanning membrane and K+-dependent Na+,H+-PPase. Heterologous expression of CmPP could significantly enhance the salt tolerance of both Escherichia coli and Saccharomyces cerevisiae, and this effect in yeast could be fortified by N-terminal addition of a vacuole-targeting signal peptide from the H+-PPase of Trypanosoma cruzi. Furthermore, introduction of CmPP could remarkably improve the salt tolerance of tobacco, implying its potential use in constructing salt-resistant transgenic crops. Consequently, the possible mechanisms of CmPP to underlie salt tolerance are discussed.

5.
J Asian Nat Prod Res ; 15(5): 433-40, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23600754

RESUMO

The microbiological transformation of the triterpene nigranoic acid (3,4-secocycloarta-4(28),24(Z)-diene-3,26-dioic acid) (1) to 3,4-secocycloarta-4(28),17(20),24(Z)-triene-7ß-hydroxy-16ß,26-lactone-3-oic acid (2) and 3,4-secocycloarta-4(28),17(20)(Z),24(Z)-triene-7ß-hydroxy-16ß-methoxy-3,26-dioic acid (3) by the freshwater fungus Dictyosporium heptasporum YMF1.01213 has been demonstrated. The structures of the biotransformation products were determined by spectroscopic and MS analyses. Compound 2, characterized by the presence of a formed C-16/C-26 ester bridge, provided a novel nine-membered lactone ring structural skeleton for 3,4-secocycloartane triterpenoid derivatives. In addition, Compounds 1-3 exhibited weak anti-HIV activity in vitro. Compounds 2 and 3 were reported for the first time as natural product derivatives.


Assuntos
Fármacos Anti-HIV/metabolismo , Fungos/metabolismo , Triterpenos/metabolismo , Fármacos Anti-HIV/química , Biotransformação , Água Doce/microbiologia , Humanos , Ressonância Magnética Nuclear Biomolecular , Triterpenos/química , Triterpenos/farmacologia
6.
Planta Med ; 78(17): 1837-43, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23096258

RESUMO

Six new dibenzo[b,e]oxepinone metabolites, chaetones A-F (1-6), as well as three known compounds, 1-hydroxy-6-methyl-8-hydroxymethylxanthone (7), citreorosein (8), and emodin (9), were obtained from a freshwater-derived fungal strain Chaetomium sp. YMF 1.02105. Their structures were established on the basis of extensive spectroscopic data analysis and comparison with spectroscopic data reported. Compounds 1-6 are further additions to the small group of dibenzo[b,e]oxepinones represented by arugosins A-H. Compounds 1-7 were tested for their cytotoxic activities against A549, Raji, HepG2, MCF-7, and HL-60 cell lines. The results showed that compound 3 had significant cytotoxicity with IC50 values of 1.2, 1.8, 1.9, 2.3, and 1.6 µg/mL, respectively, against the five cancer cell lines. All compounds showed modest antimicrobial activity against Staphylococcus aureus (ATCC 6538) in standard disk assays.


Assuntos
Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Chaetomium/química , Citotoxinas/isolamento & purificação , Citotoxinas/farmacologia , Antibacterianos/química , Linhagem Celular Tumoral/efeitos dos fármacos , Citotoxinas/química , Dibenzoxepinas/química , Dibenzoxepinas/isolamento & purificação , Dibenzoxepinas/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Água Doce/microbiologia , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Staphylococcus aureus/efeitos dos fármacos
7.
Bioorg Med Chem Lett ; 21(3): 961-5, 2011 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-21232955

RESUMO

Four new cycloartane triterpenoids, angustific acid A (1), angustific acid B (2), angustifodilactone A (3) and angustifodilactone B (4) were isolated from the branches of Kadsura angustifolia together with six known compounds, micranoic acid B (5), nigranoic acid (6), schisandrin (7), schisantherin D (8), interiotherin B (9), schisantherin B (10). Their structures were established on the basis of extensive spectroscopic data analyses and comparison with spectroscopic data reported. Compound 1, characterized by the presence of a C-16/C-17, C-20/C-21 conjugated diene and a C-1/C-7 ester bridge formed in rings A and B, provided a novel structural skeleton for 3,4-secocycloartane triterpenoid derivatives. In addition, the anti-HIV activities of these compounds were determined in infected C8166 cells, and it was found that angustific acid A (1) exhibited the most potent anti-HIV activity with an EC(50) value of 6.1 µg/mL and a therapeutic index of more than 32.8.


Assuntos
Fármacos Anti-HIV/química , HIV/efeitos dos fármacos , Kadsura/química , Triterpenos/química , Fármacos Anti-HIV/isolamento & purificação , Fármacos Anti-HIV/toxicidade , Linhagem Celular Tumoral , Humanos , Espectroscopia de Ressonância Magnética , Conformação Molecular , Caules de Planta/química , Triterpenos/isolamento & purificação , Triterpenos/toxicidade
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