C-glycosides are an important class of bioactive natural products,and the C-glycosidic bonds are usually catalyzed by C-glycosyltransferases.In this work,an efficient and rare CGT,LaCGT1,was discovered from the aquatic plant Lemna aequinoctialis.LaCGT1 could accept five sugar donors(UDP-Glc/-Xyl/-Gal/-GlcNAc/-Ara)to catalyze C-glycosylation,and showed strong preference to uridine 5′-diphosphate xylose(UDP-Xyl).LaCGT1 catalyzed at least six substrates using UDP-Xyl as sugar donor,with conversion rates of>95%.Three xylosides were obtained by scaled-up enzymatic catalysis,and their structures were identified by 1D NMR,2D NMR,and HR-ESIMS data analyses.Molecular modeling and site-directed mutagenesis indicated that R271,W357,D378,and Q379 residues were key amino acids contributing to sugar donor recognition of UDP-Xyl.LaCGT1 could be a promising catalyst to prepare bioactive flavonoid C-xylosides.
Sharpkate ShakerZhi-Min HuZi-Long WangGuo YeJin-Chen LongXin-Fang ZhaiXue QiaoMin Ye
通过水培试验,以青萍(Lemna minor L)为研究材料,研究不同浓度砷胁迫对青萍生物量、荧光参数、快速光响应和砷富集量的影响。结果显示,随着砷处理浓度增加,青萍生物量、有效量子产量Y(Ⅱ)、潜在光化学效率(F_(v)/F_(o))、最大光化学效率(F_(v)/F_(m))和光化学荧光淬灭系数(q_(P))显著下降(P<0.05),非调节性能量耗散量子产量Y(NO)、调节性能量耗散量子产量Y(NPQ)和砷单位富集量显著上升(P<0.05),非光化学淬灭系数(q_(N))先升后降。电子传递效率(ETR)随着砷处理浓度增大,呈显著下降的趋势;然而当有效辐射强度(PAR)增大时,ETR呈先升后逐渐趋于平稳的趋势。本研究表明,青萍在受到砷胁迫时,可通过调节PSⅡ反应中心进行自我保护,缓解砷毒害;对于低浓度(As^(3+)≤3mg·L^(-1))时,则表现出一定耐受性,且砷浓度越高,青萍对砷单位富集量越大。然而,当为高砷处理浓度时,则产生严重抑制作用。本研究可为青萍修复As^(3+)污染水体提供参考意义。
研究不同质量浓度(0、0.5、1.0、1.5、2.5 mg/L)Cu^(2+)胁迫下浮萍(Lemna minor L.)叶片的叶绿素含量、可溶性蛋白含量和丙二醛(MDA)浓度以及对保护酶—超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的影响。结果表明,在Cu^(2+)处理条件下,随着Cu^(2+)质量浓度的升高,叶绿素含量和可溶性蛋白含量逐渐下降,而丙二醛(MDA)浓度则逐渐上升;SOD和POD活性都在Cu2+质量浓度为1.0 mg/L时达到最高值,其后随着Cu2+质量浓度的升高,活性逐渐降低。
The study focused on the change in land-use and phytoremediation and biosorption efficacy of Lead and Cadmium from the petroleum-contaminated water by Lemna minor L. and Azolla pinnata. For the study of the change in land-use in Paloich, satellite imagery of Paloich between 2000 and 2020 was obtained from http://www.earthexplore.usgs.org/ and analyses. Water samples were collected at different points of Paloich. Experimental set-up consisted of four main samples sets viz:Lemna minor L. and petroleum
