The recent explosive outbreak of Zika virus （ZlKV） infection has been reported in South and Central America and the Caribbean. Neonatal microcephaly associated with ZIKV infection has already caused a public health ...The recent explosive outbreak of Zika virus （ZlKV） infection has been reported in South and Central America and the Caribbean. Neonatal microcephaly associated with ZIKV infection has already caused a public health emergency of international concern. No specific vaccines or drugs are currently available to treat ZIKV infection. The ZIKV helicase, which plays a pivotal role in viral RNA replication, is an attractive tar- get for therapy. We determined the crystal structures of ZIKV helicase-ATP-Mnz＋ and ZlKV helicase-RNA. This is the first structure of any flavivirus helicase bound to ATP. Comparisons with related flavivirus helicases have shown that although the critical P-loop in the active site has variable conformations among different species, it adopts an identical mode to recognize ATPIMn2＋. The structure of ZlKV helicase-RNA has revealed that upon RNA binding, rotations of the motor domains can cause significant conformational changes. Strikingly, although ZlKV and dengue virus （DENV） apo-helicases share conserved residues for RNA binding, their different manners of motor domain rotations result in distinct individual modes for RNA recognition. It suggests that flavivirus helicases could have evolved a conserved engine to convert chemical energy from nucleoside triphosphate to mechanical energy for RNA unwinding, but different motor domain rotations result in variable RNA recognition modes to adapt to individual viral replication.展开更多
Panax quinquefolium is a perennial herbaceous plant that contains many beneficial ginsenosides with diverse pharmacological effects.24(R)-pseudoginsenoside F_(11)is specific to P.quinquefolium,a useful biomarker for d...Panax quinquefolium is a perennial herbaceous plant that contains many beneficial ginsenosides with diverse pharmacological effects.24(R)-pseudoginsenoside F_(11)is specific to P.quinquefolium,a useful biomarker for distinguishing this species from other related plants.However,because of its nonconjugated property and the complexity of existing detection methods,this biomarker cannot be used as the identification standard.We herein present a stable 24(R)-pseudoginsenoside F_(11)fingerprint spectrum in the terahertz band,thereby proving that F_(11)can be detected and quantitatively analyzed via terahertz spectroscopy.We also analyzed the sample by high-performance liquid chromatography-triple quadrupole mass spectrometry.The difference between the normalized data for the two analytical methods was less than 5%.Furthermore,P.quinquefolium from different areas and other substances can be clearly distinguished based on these terahertz spectra with a standard principal component analysis.Our method is a fast,simple,and cost-effective approach for identifying and quantitatively analyzing P.quinquefolium.展开更多
文摘The recent explosive outbreak of Zika virus （ZlKV） infection has been reported in South and Central America and the Caribbean. Neonatal microcephaly associated with ZIKV infection has already caused a public health emergency of international concern. No specific vaccines or drugs are currently available to treat ZIKV infection. The ZIKV helicase, which plays a pivotal role in viral RNA replication, is an attractive tar- get for therapy. We determined the crystal structures of ZIKV helicase-ATP-Mnz＋ and ZlKV helicase-RNA. This is the first structure of any flavivirus helicase bound to ATP. Comparisons with related flavivirus helicases have shown that although the critical P-loop in the active site has variable conformations among different species, it adopts an identical mode to recognize ATPIMn2＋. The structure of ZlKV helicase-RNA has revealed that upon RNA binding, rotations of the motor domains can cause significant conformational changes. Strikingly, although ZlKV and dengue virus （DENV） apo-helicases share conserved residues for RNA binding, their different manners of motor domain rotations result in distinct individual modes for RNA recognition. It suggests that flavivirus helicases could have evolved a conserved engine to convert chemical energy from nucleoside triphosphate to mechanical energy for RNA unwinding, but different motor domain rotations result in variable RNA recognition modes to adapt to individual viral replication.
文摘Panax quinquefolium is a perennial herbaceous plant that contains many beneficial ginsenosides with diverse pharmacological effects.24(R)-pseudoginsenoside F_(11)is specific to P.quinquefolium,a useful biomarker for distinguishing this species from other related plants.However,because of its nonconjugated property and the complexity of existing detection methods,this biomarker cannot be used as the identification standard.We herein present a stable 24(R)-pseudoginsenoside F_(11)fingerprint spectrum in the terahertz band,thereby proving that F_(11)can be detected and quantitatively analyzed via terahertz spectroscopy.We also analyzed the sample by high-performance liquid chromatography-triple quadrupole mass spectrometry.The difference between the normalized data for the two analytical methods was less than 5%.Furthermore,P.quinquefolium from different areas and other substances can be clearly distinguished based on these terahertz spectra with a standard principal component analysis.Our method is a fast,simple,and cost-effective approach for identifying and quantitatively analyzing P.quinquefolium.
