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The enantioselective mechanism of the esterase QeH against the two enantiomers of quizalofop–ethyl (QE) has been primitively studied using computational and experimental approaches. However, it is still unclear how the esterase QeH adjusts its conformation to adapt to substrate binding and promote enzyme–substrate interactions in the catalytic kinetics. The equilibrium processes of enzyme–substrate interactions and catalytic dynamics were reproduced by performing independent molecular dynamics (MD) runs on the QeH-(R)/(S)-QE complexes with a newly developed residue-specific force field (RSFF2C). Our results indicated that the benzene ring of the (R)-QE structure can simultaneously form anion–π and cation–π interactions with the side-chain group of Glu328 and Arg384 in the binding cavity of the QeH-(R)-QE complex, resulting in (R)-QE being closer to its catalytic triplet system (Ser78-Lys81-Tyr189) with the distances measured for the hydroxyl oxygen atom of the catalytic Ser78 of QeH and the carbonyl carbon atom of (R)-QE of 7.39 Å, compared to the 8.87 Å for (S)-QE, whereas the (S)-QE structure can only form an anion–π interaction with the side chain of Glu328 in the QeH-(S)-QE complex, being less close to its catalytic site. The computational alanine scanning mutation (CAS) calculations further demonstrated that the π–π stacking interaction between the indole ring of Trp351 and the benzene ring of (R)/(S)-QE contributed a lot to the binding stability of the enzyme–substrate (QeH-(R)/(S)-QE). These results facilitate the understanding of their catalytic processes and provide new theoretical guidance for the directional design of other key enzymes for the initial degradation of aryloxyphenoxypropionate (AOPP) herbicides with higher catalytic efficiencies. [ABSTRACT FROM AUTHOR]

Event fragments as the smallestr unit was defined and a two-stage event fragments temporal relation recognition algorithm was proposed.The first stage is sequential mapping and the second is sequence recognition.The real online data increased accuracy by 4% compared to common classifier and strong rule algorithm.

To reveal the invasion mechanism of an alien noxious weed-Alternanthera philoxeroides and reduce or ultimately eliminate its damage, physiological responses of A. philoxeroides and A. pungens with a relatively weak invasion capacity to photooxidative stress (induced by 10 μmol . L-1 methyl viologen at light intensity of 100 μmol . m-2 . s-1) were investigated and compared in the present study. Under photooxidative stress, the contents of chlorophyl, carotenoids, total phenolics and flavonoids in A. philoxeroides and A. pungens significantly decreased and leaf cel death rate corespondingly increased, but the former showed a higher tolerance to photooxidative stress, which might be related to total phenolic, flavonoid and DPPH. scavenging capacity in A. philoxeroides. This could be used to explain why A. philoxeroides had more stable photosystem, greater invasion capacity and higher damage. [ABSTRACT FROM AUTHOR]

In this study, supported nonmetal (boron) doping TiO2 coating photocatalysts were prepared by chemical vapor deposition (CVD) to enhance the activity under visible light irradiation and avoid the recovering of TiO2. Boron atoms were successfully doped into the lattice of TiO2 through CVD, as evidenced from XPS analysis. B-doped TiO2 coating catalysts showed drastic and strong absorption in the visible light range with a red shift in the band gap transition. This novel B-TiO2 coating photocatalyst showed higher photocatalytic activity in methyl orange degradation under visible light irradiation than that of the pure TiO2 photocatalyst. [ABSTRACT FROM AUTHOR]

A novel metallo-organic chemical vapor deposition (MOCVD) technique has been applied to the preparation of the photocatalytic titanium dioxide supported on activated carbon. The effects of various condition parameters such as carrier gas flow rate, source temperature and deposition temperature on the deposition rate were investigated. The maximum deposition rate of 8.2 mg/(g·h) was obtained under conditions of carrier gas flow rate of 400 ml/min, source temperature of 423 K and deposition temperature of 913 K. The deposition rate followed Arrhenius behavior at temperature of 753 K to 913 K, corresponding to activation energy E a of 51.09 kJ/mol. TiO2 existed only in anatase phase when the deposition temperature was 773 K to 973 K. With increase of deposition temperature from 1073 K to 1273 K, the rutile content sharply increased from 7% to 70%. It was found that a deposition temperature of 773 K and a higher source temperature of 448 K resulted in finely dispersed TiO2 particles, which were mainly in the range of 10–20 nm. [ABSTRACT FROM AUTHOR]

Identification and analysis of the whole genome of the marine-derived fungus Penicillium brasilianum HBU-136 revealed the presence of an interesting biosynthetic gene cluster (BGC) for non-ribosomal peptide synthetases (NRPS), highly homologous to the BGCs of indole-diketopiperazine derivatives. With the aid of genomic analysis, eight indole-diketopiperazines (1−8), including three new compounds, spirotryprostatin G (1), and cyclotryprostatins F and G (2 and 3), were obtained by large-scale cultivation of the fungal strain HBU-136 using rice medium with 1.0% MgCl2. The absolute configurations of 1−3 were determined by comparison of their experimental electronic circular dichroism (ECD) with calculated ECD spectra. Selective cytotoxicities were observed for compounds 1 and 4 against HL-60 cell line with the IC50 values of 6.0 and 7.9 μM, respectively, whereas 2, 3, and 5 against MCF-7 cell line with the IC50 values of 7.6, 10.8, and 5.1 μM, respectively. [ABSTRACT FROM AUTHOR]

The enantioselective mechanism of the esterase QeH against the two enantiomers of quizalofop-ethyl (QE) has been primitively studied using computational and experimental approaches. However, it is still unclear how the esterase QeH adjusts its conformation to adapt to substrate binding and promote enzym e-substrate interactions in the catalytic kinetics. The equilibrium processes of enzyme-subst rate interactions and catalytic dynamics were reproduced by performing independent molecular dynamics (MD) runs on the QeH-( R )/( S )-QE complexes with a newly developed residue-specific force field (RSFF2C). Our results indicated that the benzene ring of the ( R )-QE structure can simultaneously form anion-π and cation-π interactions with the side-chain group of Glu328 and Arg384 in the binding cavity of the QeH-( R )-QE complex, resulting in ( R )-QE being closer to its catalytic triplet system (Ser78-Lys81-Tyr189) with the distances measured for the hydroxyl oxygen atom of the catalytic Ser78 of QeH and the carbonyl carbon atom of ( R )-QE of 7.39 Å, compared to the 8.87 Å for (S)-QE, whereas the ( S )-QE structure can only form an anion-π interaction with the side chain of Glu328 in the QeH-( S )-QE complex, being less close to its catalytic site. The computational alanine scanning mutation (CAS) calculations further demonstrated that the π-π stacking interaction between the indole ring of Trp351 and the benzene ring of ( R )/( S )-QE contributed a lot to the binding stability of the enzyme-substrate (QeH-( R )/( S )-QE). These results facilitate the understanding of their catalytic processes and provide new theoretical guidance for the directional design of other key enzymes for the initial degradation of aryloxyphenoxypropionate (AOPP) herbicides with higher catalytic efficiencies.

Marine-derived fungi are a rich source of structurally diverse metabolites. Fungi produce an array of compounds when grown under different cultivation conditions. In the present work, different media were used to cultivate the fungus Aspergillus sp. ZA-01, which was previously studied for the production of bioactive compounds, and three new prenylxanthone derivatives, aspergixanthones I⁻K ( 1 ⁻ 3 ), and four known analogues ( 4 ⁻ 7 ) were obtained. The absolute configuration of 1 was assigned by ECD experiment and the Mo₂(AcO)₄ ICD spectrum of its methanolysis derivative ( 1a ). All the compounds ( 1 ⁻ 7 ) were evaluated for their anti- Vibrio activities. Aspergixanthone I ( 1 ) showed the strongest anti- Vibrio activity against Vibrio parahemolyticus (MIC = 1.56 μM), Vibrio anguillarum (MIC = 1.56 μM), and Vibrio alginolyticus (MIC = 3.12 μM).