Phenylpropanoids 是一类在植物中发现的丰富的结构单元,来源于苯丙氨酸和酪氨酸。苯丙烷聚合产生第二丰富的生物聚合物木质素,而立体和位点选择性偶联产生一系列具有强生物活性的木脂素天然产物,包括拓扑异构酶抑制剂和化疗药物依托泊苷。依托泊苷生物合成的一个关键步骤涉及一种植物指示蛋白,该蛋白促进松柏醇(一种常见的苯丙素)选择性二聚化,形成 (+)-松脂醇,一种关键的 C 2对称通路中间体。尽管这种偶联反应具有优雅和快速组装依托泊苷支架的能力,但尚未利用定向蛋白来生成其他复杂的木脂素天然产物。在这里,我们证明了来自鬼臼属植物的致敏蛋白与漆酶结合可以引导异源天然和合成松柏醇类似物的偶联,用于松脂醇类似物的对映选择性合成。这种复杂性产生的途径非常直接和有效:三个新键和四个立体中心在一个步骤中由两种不同的非手性单体产生。我们预计我们的结果将使难以获得的非天然木脂素类似物和依托泊苷衍生物的生物
A method of selectively reacting lignin or a lignin-derived reactant to yield an aromatic product. The method includes the step of reacting lignin or a lignin-derived reactant with a molybdenum-containing catalyst, in a solvent, and optionally in the presence of an oxidant, for a time and a temperature wherein at least a portion of the lignin or lignin-derived reactant is selectively converted into an aromatic product, preferably coniferaldehyde and/or sinapaldehyde.
Flexible Method for Conjugation of Phenolic Lignin Model Compounds to Carrier Proteins
作者:Ruili Gao、Fachuang Lu、Yimin Zhu、Michael G. Hahn、John Ralph
DOI:10.1021/acs.jafc.6b04273
日期:2016.10.19
with the number of dimers per carrier protein being as high as 50; NMR experiments on a 15N- and 13C-labeled conjugation product indicated that 13 dimers were added to the native lysine residues and the remainder (∼37) to the amine moieties on the ethylenediamine linkers added to BSA; ∼32% of the available primary amine groups on cBSA were therefore conjugated to the hapten. This loading is suitable for
Incorporation of catechyl monomers into lignins: lignification from the non-phenolic end <i>via</i> Diels–Alder cycloaddition?
作者:Daisuke Ando、Fachuang Lu、Hoon Kim、Alexis Eugene、Yuki Tobimatsu、Ruben Vanholme、Thomas J. Elder、Wout Boerjan、John Ralph
DOI:10.1039/d1gc03022a
日期:——
diene in a hetero-Diels–Alder reaction, a benzodioxane structure was produced with a different regiochemistry than the benzodioxane isomer produced viaradical coupling; (ii) when the quinone's diene participated in the Diels–Alderreaction, a distinctive oxatricyclo structure was produced. Both features may be used as markers for the occurrence of Diels–Alderreactions in lignification. Examination
Hitherto Unrecognized Fluorescence Properties of Coniferyl Alcohol
作者:Komandoor Elayavalli Achyuthan、Paul David Adams、Supratim Datta、Blake Alexander Simmons、Anup Kumar Singh
DOI:10.3390/molecules15031645
日期:——
We instituted a quasi-quality assurance program for demonstrating coniferyl alcohol’s fluorescence and fluorescence diminishment following enzymatic oxidation. The magnitude of diminishment was a measure of catalysis. High throughput screening was performed in pseudo-kinetic and endpoint modes by measuring the fluorescence at 416 nm following excitation at 290, 310 or 340 nm. Dose-response tracings were linear between two and three orders of magnitude with average limits of detection and quantitation of 1.8 and 6.9 mM coniferyl alcohol, respectively. Oxidation was evident with 0.025 mg/mL laccase or 0.003 mg/mL peroxidase or inside 5 min using 0.5 mg/mL laccase or 5 mM substrate. Sodium chloride inhibited (IC50, 25 mM) laccase oxidation of coniferyl alcohol. Fluorescence from 10 concentrations (1 to 1000 mM) of coniferyl alcohol was stable for 24 hours over 14 excitation/emission cycles at 3 different combinations of excitation and emission wavelengths. In conclusion, coniferyl alcohol absorption and fluorescence assays should facilitate biomass lignin analyses and improve delignification.
Lignin Chemistry: Biosynthetic Study and Structural Characterisation of Coniferyl Alcohol Oligomers Formed In Vitro in a Micellar Environment
作者:Samantha Reale、Francesca Attanasio、Nicoletta Spreti、Francesco De Angelis
DOI:10.1002/chem.200903302
日期:2010.5.25
generated in it, represent a closer mimicry of the natural microenvironment since an enzyme, under micellar conditions, reproduces the cell system better than in buffer alone. On the basis of the oligomers structures a new biosynthetic perspective was proposed that focused attention on a coniferylalcohol dimeric quinone methide as the key intermediate of the reaction. A formal, strictly alternate sequence
松柏醇木质素模型(所谓的脱氢聚合产物,DHP)是在均质条件下通过胶束化阳离子表面活性剂的存在而在水中制备的。报告了在我们的反应条件下对酶系统过氧化物酶/ H 2 O 2的活性的完整研究,直至五聚体的所有反应产物的特征均是11 H NMR光谱和ESI质谱。我们的系统以及在其中生成的分子代表了自然的微环境的近似模拟,因为在胶束条件下,酶比仅在缓冲液中能更好地复制细胞系统。在低聚物结构的基础上,提出了新的生物合成观点,该观点将注意力集中在作为反应的关键中间体的松柏油基二聚体醌甲基化物上。自由基和离子步骤的正式,严格交替的序列强调了该反应,从而生成有序的寡聚寡核苷酸结构。作为其他模型木质素的替代品,我们的木质素在低聚物单元之间的自由基偶联程度较低。这为观察到细胞壁中自由基产生的速率较低提供了更接近的生物合成情况。