10 research outputs found
Chemical Synthesis of Natural Polyubiquitin Chains through Auxiliary-Mediated Ligation of an Expressed Ubiquitin Isomer
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 lā2-Aryl-Amino Acids by a Chemoenzymatic Route
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>2aāe</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
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).
<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 treatment, BOF treatment on bacterial wilt incidence, biocontrol efficacy of BOF and <i>R</i>. <i>solanacearum</i> densities in the rhizosphere soils and stems of tomato plants.
<p>Replicate plots were fitted as a blocking factor in the analysis.</p
The effect of transplantation time, BOF treatments and Blocks on tomato yield and income.
<p>The effect of transplantation time, BOF treatments and Blocks on tomato yield and income.</p
Changes in the mean maximum temperature (panel A) for every 10-day time period after transplantation (<i>T</i><sub><i>10</i></sub>) and in the mean maximum temperature (panel B) during the entire crop season (<i>T</i><sub><i>cs</i></sub>) for the early-spring (ES, black circle), late-spring (LS, white circle), early-autumn (EA, white triangle) and late-autumn (LA, black triangle) crop seasons transplantation treatments in 2011 and 2012.
<p>Bars show standard error of mean (SEM) in all panels. Dashed lines in all panels indicate T<sub><i>10</i></sub> or T<sub><i>cs</i></sub> equal to 25Ā°C Different letters in lowercase on the top of the bar represent significance (Duncanās multiple range test, <i>P</i> < 0.05).</p
In all panels, lines denote for the dynamics of <i>R</i>. <i>solanacearum</i> densities in the stem-bases of tomato plants in control (grey lines for means and grey circles for replicates) and BOF (black lines for means and black squares for replicates) treatments in the early-spring (panel A), late-spring (panel B), early-autumn (panel C) and late-autumn (panel D) transplantation treatments in year 2011.
<p>The increase in <i>R</i>. <i>solanacearum</i> densities over time was fitted with nonlinear regression analysis (Equation: Sigmoidal, Sigmoid, 3 Parameter). The triangles show the average maximum air temperatures for each 10-day period after transplantation.</p
The effect of transplantation time and BOF treatment on tomato yield and farmerās income (means Ā± SEM).
<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 farmerās 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.
<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 (Duncanās multiple range test, <i>P</i> < 0.05), and NS denotes for non-significant difference. Bars show SEM in all panels.</p