10 research outputs found
Characterization of the Artemisinin Binding Site for Translationally Controlled Tumor Protein (TCTP) by Bioorthogonal Click Chemistry
Despite
the fact that multiple artemisinin-alkylated proteins in Plasmodium falciparum have been identified in recent
studies, the alkylation mechanism and accurate binding site of artemisinin–protein
interaction have remained elusive. Here, we report the chemical-probe-based
enrichment of the artemisinin-binding peptide and characterization
of the artemisinin-binding site of P. falciparum translationally controlled tumor protein (TCTP). A peptide fragment
within the N-terminal region of TCTP was enriched and found to be
alkylated by an artemisinin-derived probe. MS2 fragments showed that
artemisinin could alkylate multiple amino acids from Phe12 to Tyr22
of TCTP, which was supported by labeling experiments upon site-directed
mutagenesis and computational modeling studies. Taken together, the
“capture-and-release” strategy affords consolidated
advantages previously unavailable in artemisinin–protein binding
site studies, and our results deepened the understanding of the mechanism
of protein alkylation via heme-activated artemisinin
Chemoselective Phosphination of Titanacyclobutene: A Convenient Method for Synthesis of Allylphosphine Derivatives
Titanacyclobutenes
reacted with chlorophosphine to afford titanoallylphosphines
with high chemoselectivity, and the resulting titanoallylphosphine
could be converted into functionalized allylphosphine sulfides via
reactions with various electrophiles
Copper-Mediated Reaction of Zirconacyclopentadienes with Azides: A One-Pot Three-Component Synthesis of Multiply Substituted Pyrroles from One Azide and Two Alkynes
A general
method for the synthesis of multiply substituted pyrroles
through zirconocene-mediated coupling of two alkynes and an azide
in the presence of CuCl has been achieved
Copper-Mediated Amidation of Alkenylzirconocenes with Acyl Azides: Formation of Enamides
Copper-mediated amidation of alkenylzirconocenes generated in situ from alkynes and zirconocenes with acyl azides is accomplished under mild conditions. The reaction can be used to prepare various enamides
Site-Selective Protein Immobilization by Covalent Modification of GST Fusion Proteins
The immobilization of functional
proteins onto solid supports using
affinity tags is an attractive approach in recent development of protein
microarray technologies. Among the commonly used fusion protein tags,
glutathione <i>S</i>-transferase (GST) proteins have been
indispensable tools for protein–protein interaction studies
and have extensive applications in recombinant protein purification
and reversible protein immobilization. Here, by utilizing pyrimidine-based
small-molecule probes with a sulfonyl fluoride reactive group, we
report a novel and general approach for site-selective immobilization
of Schistosoma japonicum GST (<i>sj</i>GST) fusion proteins through irreversible and specific
covalent modification of the tyrosine-111 residue of the <i>sj</i>GST tag. As demonstrated by <i>sj</i>GST-tagged eGFP and <i>sj</i>GST-tagged kinase activity assays, this immobilization
approach offers the advantages of high immobilization efficiency and
excellent retention of protein structure and activity
Dehydrocurvularin-loaded mPEG-PLGA nanoparticles for targeted breast cancer drug delivery: preparation, characterization, <i>in vitro</i>, and <i>in vivo</i> evaluation
Dehydrocurvularin (DCV) is a promising lead compound for anti-cancer therapy. Unfortunately, the development of DCV-based drugs has been hampered by its poor solubility and bioavailability. Herein, we prepared a DCV-loaded mPEG-PLGA nanoparticles (DCV-NPs) with improved drug properties and therapeutic efficacy. The spherical and discrete particles of DCV-NPs had a uniform diameter of 101.8 ± 0.45 nm and negative zeta potential of −22.5 ± 1.12 mV (pH = 7.4), and its entrapment efficiency (EE) and drug loading (DL) were ∼53.28 ± 1.12 and 10.23 ± 0.30%, respectively. In vitro the release of DCV-NPs lasted for more than 120 h in a sustained-release pattern, its antiproliferation efficacy towards breast cancer cell lines (MCF-7, MDA-MB-231, and 4T1) was better than that of starting drug DCV, and it could be efficiently and rapidly internalised by breast cancer cells. In vivo DCV-NPs were gradually accumulated in tumour areas of mice and significantly suppressed tumour growth. In summary, loading water-insoluble DCV onto nanoparticles has the potential to be an effective agent for breast cancer therapy with injectable property and tumour targeting capacity.</p
Development of Photoaffinity Probe for the Discovery of Steviol Glycosides Biosynthesis Pathway in <i>Stevia rebuadiana</i> and Rapid Substrate Screening
Functional discovery
and characterization of the target enzymes
responsible for the biosynthesis pathway coded for the genes is ongoing,
and the unknown functional diversity of this class of enzymes has
been revealed by genome sequencing. Commonly, it is feasible in annotating
of biosynthetic genes of prokaryotes due to the existence of gene
clusters of secondary metabolites. However, in eukaryotes, the biosynthetic
genes are not compactly clustered in the way of prokaryotes. Hence,
it remains challenging to identify the biosynthetic pathways of newly
discovered natural products in plants. Steviol glycosides are one
class of natural sweeteners found in high abundance in the herb <i>Stevia rebaudiana</i>. Here, we applied the chemoproteomic strategy
for the proteomic profiling of the biosynthetic enzymes of steviol
glycosides in <i>Stevia rebaudiana</i>. We not only identified
a steviol-catalyzing UDP-glycosyltransferase (UGT) UGT73E1 involved
in steviol glycoside biosynthesis but also built up a probe-based
platform for the screening of potential substrates of functional uncharacterized
UGT rapidly. This approach would be a complementary tool in mining
novel synthetic parts for assembling of synthetic biological systems
for the biosynthesis of other complex natural products
Development of Photoaffinity Probe for the Discovery of Steviol Glycosides Biosynthesis Pathway in <i>Stevia rebuadiana</i> and Rapid Substrate Screening
Functional discovery
and characterization of the target enzymes
responsible for the biosynthesis pathway coded for the genes is ongoing,
and the unknown functional diversity of this class of enzymes has
been revealed by genome sequencing. Commonly, it is feasible in annotating
of biosynthetic genes of prokaryotes due to the existence of gene
clusters of secondary metabolites. However, in eukaryotes, the biosynthetic
genes are not compactly clustered in the way of prokaryotes. Hence,
it remains challenging to identify the biosynthetic pathways of newly
discovered natural products in plants. Steviol glycosides are one
class of natural sweeteners found in high abundance in the herb <i>Stevia rebaudiana</i>. Here, we applied the chemoproteomic strategy
for the proteomic profiling of the biosynthetic enzymes of steviol
glycosides in <i>Stevia rebaudiana</i>. We not only identified
a steviol-catalyzing UDP-glycosyltransferase (UGT) UGT73E1 involved
in steviol glycoside biosynthesis but also built up a probe-based
platform for the screening of potential substrates of functional uncharacterized
UGT rapidly. This approach would be a complementary tool in mining
novel synthetic parts for assembling of synthetic biological systems
for the biosynthesis of other complex natural products
Discovery of a Series of 2,5-Diaminopyrimidine Covalent Irreversible Inhibitors of Bruton’s Tyrosine Kinase with in Vivo Antitumor Activity
Bruton’s tyrosine kinase (Btk)
is an attractive drug target for treating several B-cell lineage cancers.
Ibrutinib is a first-in-class covalent irreversible Btk inhibitor
and has demonstrated impressive effects in multiple clinical trials.
Herein, we present a series of novel 2,5-diaminopyrimidine covalent
irreversible inhibitors of Btk. Compared with ibrutinib, these inhibitors
exhibited a different selectivity profile for the analyzed kinases
as well as a dual-action mode of inhibition of both Btk activation
and catalytic activity, which counteracts a negative regulation loop
for Btk. Two compounds from this series, <b>31</b> and <b>38</b>, showed potent antiproliferative activities toward multiple
B-cell lymphoma cell lines, including germinal center B-cell-like
diffuse large B cell lymphoma (GCB-DLBCL) cells. In addition, compound <b>31</b> significantly prevented tumor growth in a mouse xenograft
model
Nicosulfuron Biodegradation by a Novel Cold-Adapted Strain Oceanisphaera psychrotolerans LAM-WHM-ZC
Nicosulfuron
is a common environmental pollutant, posing a great
threat to aquatic systems and causing significant damage to crops.
This study reported a cold-adapted strain Oceanisphaera
psychrotolerans LAM-WHM-ZC, which efficiently degrades
nicosulfuron over a wide range of temperatures (5 to 40 °C).
The Box–Behnken design method was used to optimize the degradation
conditions. O. psychrotolerans LAM-WHM-ZC
can degrade 92.4% and 74.6% of initially supplemented 100 mg/L nicosulfuron
under the optimum and low temperature of 18.1 and 5 °C, respectively,
within 7 days. O. psychrotolerans LAM-WHM-ZC
was found to be highly efficient in degrading cinosulfuron, chlorsulfuron,
rimsulfuron, bensulfuron methyl, and ethametsulfuron methyl. Metabolites
from nicosulfuron degradation were identified by UPLC-MS, and a possible
degradation pathway was proposed. Furthermore, O. psychrotolerans LAM-WHM-ZC can also degrade nicosulfuron in soil; 78.6% and 67.4%
of the initial nicosulfuron supplemented at 50 mg/kg were removed
at 18.1 and 5 °C, respectively, within 15 days