10 research outputs found

    Chemical Synthesis of Natural Polyubiquitin Chains through Auxiliary-Mediated Ligation of an Expressed Ubiquitin Isomer

    No full text
    An efficient method for the assembly of polyUb chains using auxiliary-modified Ub isomers is reported. This strategy takes advantages of auxiliary-mediated native chemical ligation between the distal Ub C-terminal hydrazide and the auxiliary of proximal Ub. Using removable protecting groups, Lys48-linked and Lys6-linked tri-Ub and even a mixed-linkage Lys6, Lys48-linked triUb in multimilligram quantities was made. These results demonstrate that this strategy yields natural polyubiquitin chains of desired length and linkage by using Ub isomer

    Efficient Synthesis of Non-Natural lā€‘2-Aryl-Amino Acids by a Chemoenzymatic Route

    No full text
    Enantiopure non-natural 2-aryl-amino acids are important intermediates for synthesizing pharmaceuticals. To develop an efficient chemoenzymatic process to produce non-natural 2-aryl-amino acids, a penicillin G acylase (PGA) gene from <i>Bacillus megaterium</i> was cloned and expressed in <i>Bacillus subtilis</i> WB800. The recombinant PGA exhibited a high hydrolytic activity and excellent enantioselectivity (<i>E</i> > 200) toward <i>N</i>-phenylacetyl derivatives of non-natural 2-aryl-amino acids. The l-2-aryl-amino acids were obtained in >99.9% enantiomeric excess (ee) and >49% conversion within 3 h. The position and type of the substituent in the substrate influence the recombinant PGA activity but do not affect the PGA enantioselectivity. The kinetic parameters of the recombinant PGA for different substrates were determined and compared. The mechanisms of enantioselectivity of PGA with respect to different substrates were elucidated. The chiral discrimination of PGA with respect to <i>rac</i>-<b>2aā€“e</b> was mainly because the d-substrates used in this study cannot interact with the active residues and bind to the active pocket as stably as the l-substrates. The unreacted <i>N</i>-phenylacetyl-d-2-aryl-amino acids can be completely racemized at 170 Ā°C and then used as the substrate. A gram-scale production of l-2-aryl-amino acids was successfully achieved with approximately theoretical conversion, indicating that the chemoenzymatic approach appears to be promising for industrial applications

    PPARĪ± Mediates the Hepatoprotective Effects of Nutmeg

    No full text
    Nutmeg is a Traditional Chinese Medicine used to treat gastrointestinal diseases. Some reports have indicated that nutmeg has hepatoprotective activity. In this study, a thioacetamide (TAA)-induced acute liver injury model in mice was used to explore the mechanism of the protective effects of nutmeg extract (NME), including its major bioactive component myrislignan. The results indicated that NME could effectively protect TAA-induced liver damage as assessed by recovery of increased serumtransaminases, decrease in hepatic oxidative stress, and lower hepatic inflammation. Metabolomics analysis further revealed that treatment with NME led to the recovery of a series of lipids including lysophosphatidylcholines that were decreased and a lowering of acylcarnitines that were increased in mouse plasma and liver after TAA exposure. Gene expression analysis demonstrated that the hepatoprotective effect of NME was achieved by modulation of the peroxisome proliferator-activated receptor alpha (PPARĪ±) as well as the decrease in oxidative stress. NME could not protect from TAA-induced liver injury in <i>Ppara</i><b>-</b>null mice, suggesting that its protective effect was dependent on PPARĪ±. Myrislignan, a representative neolignan in nutmeg, showed potent protective activity against TAA-induced liver toxicity. These data demonstrate that nutmeg alleviates TAA-induced liver injury through the modulation of PPARĪ± and that the lignan compounds in nutmeg such as myrislignan partly contributed to this action

    Nonlinear regression analyses (Equation: Sigmoidal, Sigmoid, 3-Parameter) between mean maximum temperature averaged over crop season (<i>T</i><sub><i>cs</i></sub>) and both biocontrol efficacy of BOF (black line) and disease incidence in control treatment (grey line).

    No full text
    <p>Nonlinear regression analyses (Equation: Sigmoidal, Sigmoid, 3-Parameter) between mean maximum temperature averaged over crop season (<i>T</i><sub><i>cs</i></sub>) and both biocontrol efficacy of BOF (black line) and disease incidence in control treatment (grey line).</p

    The effect of transplantation time and BOF treatment on tomato yield and farmerā€™s income (means Ā± SEM).

    No full text
    <p>Yield denotes for mean yield for five replicate plots per treatment. Price and income are shown in Chinese Yuans (RMB). The price of tomato denotes for market price of the time based on farmerā€™s accounting.</p

    Disease incidence (DI) and biocontrol efficacy (BCE of BOF) for untreated grey bars) and BOF-treated tomato plants (bio-organic fertilizer, black bars) in the early-spring (ES), late-spring (LS), early-autumn (EA) and late-autumn (LA) transplantation treatments in 2011 and 2012.

    No full text
    <p>Panel B shows <i>R</i>. <i>solanacearum</i> densities in the rhizosphere soil in the beginning of harvest. In all panels, asterisks denote for statistically significant difference between BOF and control treatments (Duncanā€™s multiple range test, <i>P</i> < 0.05), and NS denotes for non-significant difference. Bars show SEM in all panels.</p
    corecore