6 research outputs found
DataSheet_1_Molecular cloning and functional characterization of BcTSA in the biosynthesis of indole alkaloids in Baphicacanthus cusia.docx
Baphicacanthus cusia (Nees) Bremek (B. cusia) is an essential traditional Chinese herb that is commonly used to treat colds, fever, and influenza. Indole alkaloids, such as indigo and indirubin, are the primary active constituents of B. cusia. The indole-producing reaction is crucial for regulating the flow of indole alkaloids metabolites along the pathways and coordinating primary and secondary product biosynthesis in plants. The tryptophan synthase alpha-subunit (TSA) can catalyse a process that produces indole, which is free to enter secondary metabolite pathways; however, the underlying potential mechanism of regulating indigo alkaloids synthesis remains unknown. Here, a BcTSA was cloned from the transcriptome of B. cusia. The BcTSA has a significant degree of similarity with other plant TSAs according to bioinformatics and phylogenetic analyses. Quantitative real-time PCR (RT-qPCR) research showed that BcTSA was dramatically enhanced in response to treatment with methyl jasmonate (MeJA), salicylic acid (SA), and abscisic acid (ABA), and was predominantly expressed in the stems as opposed to the leaves and rhizomes. Subcellular localization revealed that BcTSA is localized in chloroplasts, which is compatible with the fact that the conversion of indole-3-glycerol phosphate (IGP) to indole occurs in chloroplasts. The complementation assay results showed that BcTSA was functional, demonstrating that it was capable of catalyzing the conversion of IGP to indole. BcTSA was shown to stimulate the manufacture of indigo alkaloids including isatin, indigo, and indirubin when the gene was overexpressed in the hairy roots of Isatis indigotica. In conclusion, our research provides novel perspectives that might be applied to manipulating the indole alkaloid composition of B. cusia.</p
Toward a Unified Identification of Ti Location in the MFI Framework of High-Ti-Loaded TS-1: Combined EXAFS, XANES, and DFT Study
Titanium silicalite-1 (TS-1) has
been shown to be a heterogeneous
catalyst with remarkable efficiency and selectivity; however, the
nature of the active Ti site in the MFI framework remains elusive.
Here we report combined experimental and theoretical research on Ti
distribution in the 12 crystallographically distinct T sites of the
MFI framework in high-Ti-loaded TS-1 (2.7 wt % in TiO<sub>2</sub>).
Using a multishell fit to extended X-ray absorption fine structure,
we show that T4 is the most populated site, in marked contrast to
the preferential substitution sites and the definitely excluded sites
assumed hitherto by diffraction studies. The identification is supported
by a good agreement between calculated and experimental X-ray absorption
near-edge structure studies and by full periodic density functional
theory (DFT) computation. In spite of having the identical most favored
site, the preference order for the remaining sites predicted by DFT
does not fully match the experimental results. This suggests that
Ti distribution in the resulting TS-1 framework is positively correlated
with the thermodynamic stability of pure material but can be affected
by other factors such as interdefects. These new insights may facilitate
the bottom-up design of new zeolites with tailored catalytic performance
and studies on mechanisms of various oxidation reactions