3690-05-9Relevant articles and documents
Characterization and Elimination of Undesirable Protein Residues in Plant Cell Wall Materials for Enhancing Lignin Analysis by Solution-State Nuclear Magnetic Resonance Spectroscopy
Kim, Hoon,Padmakshan, Dharshana,Li, Yanding,Rencoret, Jorge,Hatfield, Ronald D.,Ralph, John
, p. 4184 - 4195 (2017)
Protein polymers exist in every plant cell wall preparation, and they interfere with lignin characterization and quantification. Here, we report the structural characterization of the residual protein peaks in 2D NMR spectra in corn cob and kenaf samples and note that aromatic amino acids are ubiquitous and evident in spectra from various other plants and tissues. The aromatic correlations from amino acid residues were identified and assigned as phenylalanine and tyrosine. Phenylalanine's 3/5 correlation peak is superimposed on the peak from typical lignin p-hydroxyphenyl (H-unit) structures, causing an overestimation of the H units. Protein contamination also occurs when using cellulases to prepare enzyme lignins from virtually protein-free wood samples. We used a protease to remove the protein residues from the ball-milled cell walls, and we were able to reveal H-unit structures in lignins more clearly in the 2D NMR spectra, providing a better basis for their estimation.
Action of diverse peroxidases and laccases on six cell wall-related phenolic compounds
Wallace, Graham,Fry, Stephen C.
, p. 769 - 773 (1999)
Four peroxidases and four laccases were compared as to reaction rates catalysed with six phenolic substrates of relevance to the plant cell wall. When each phenolic substrate was tested at 670 μM and pH 6.0, in the presence of 670 μM H2O2 or ~270 μM O2 as the electron acceptor, all the peroxidases and laccases had similar substrate preferences: reaction rates were in the order sinapyl > coniferyl > p-coumaryl alcohols, and feruloyl > p-coumaroyl esters. Specific activities were in the order basic peroxidase > acidic peroxidase>>laccase. The data are consistent with the view that peroxidases rather than laccases play a major role in phenolic cross-linking in the cell wall.
Comparative transcriptomics analysis for gene mining and identification of a cinnamyl alcohol dehydrogenase involved in methyleugenol biosynthesis from asarum sieboldii miq
Liu, Jinjie,Xu, Chong,Zhang, Honglei,Liu, Fawang,Ma, Dongming,Liu, Zhong
, (2018/12/13)
Asarum sieboldii Miq., one of the three original plants of TCM ASARI RADIX ET RHIZOMA, is a perennial herb distributed in central and eastern China, the Korean Peninsula, and Japan. Methyleugenol has been considered as the most important constituent of Asarum volatile oil, meanwhile asarinin is also employed as the quality control standard of ASARI RADIX ET RHIZOMA in Chinese Pharmacopeia. They both have shown wide range of biological activities. However, little was known about genes involved in biosynthesis pathways of either methyleugenol or asarinin in Asarum plants. In the present study, we performed de novo transcriptome analysis of plant tissues (e.g., roots, rhizomes, and leaves) at different developmental stages. The sequence assembly resulted in 311,597 transcripts from these plant materials, among which 925 transcripts participated in ‘secondary metabolism’ with particularly up to 20.22% of them falling into phenylpropanoid biosynthesis pathway. The corresponding enzymes belong to seven families potentially encoding phenylalanine ammonia-lyase (PAL), trans-cinnamate 4-monooxygenase (C4H), p-coumarate 3-hydroxylase (C3H), caffeoyl-CoA O-methyltransferase (CCoAOMT), cinnamoyl-CoA reductase (CCR), cinnamyl alcohol dehydrogenase (CAD), and eugenol synthase (EGS). Moreover, 5 unigenes of DIR (dirigent protein) and 11 unigenes of CYP719A (719A subfamily of cytochrome P450 oxygenases) were speculated to be involved in asarinin pathway. Of the 15 candidate CADs, four unigenes that possessed high FPKM (fragments per transcript kilobase per million fragments mapped) value in roots were cloned and characterized. Only the recombinant AsCAD5 protein efficiently converted p-coumaryl, coniferyl, and sinapyl aldehydes to their corresponding alcohols, which are key intermediates employed not only in biosynthesis of lignin but also in that of methyleugenol and asarinin. qRT-PCR revealed that AsCAD5 had a high expression level in roots at three developmental stages. Our study will provide insight into the potential application of molecular breeding and metabolic engineering for improving the quality of TCM ASARI RADIX ET RHIZOMA.
β-Cyclodextrin/IBX in water: Highly facile biomimetic one pot deprotection of THP/MOM/Ac/Ts ethers and concomitant oxidative cleavage of chalcone epoxides and oxidative dehydrogenation of alcohols
Kumar, Sumit,Ahmed, Naseem
supporting information, p. 648 - 656 (2016/02/12)
A mild and efficient one-pot deprotection of THP/MOM/Ac/Ts ethers, and concomitant oxidative cleavage of epoxides and oxidative dehydrogenation of alcohols to form β-hydroxy 1,2-diketones, 1,2,3-triketones and conjugated aromatic carbonyl systems (chalcones) using β-cyclodextrin/IBX in water has been developed. o-Iodoxybenzoic acid, a readily available hypervalent iodine(v) reagent, was found to be highly effective with β-cyclodextrin in carrying out the deprotection and subsequent transformations under an eco-friendly environment. The reaction gave moderate to excellent yields ranging from 50-99% at 60°C in 40 min to 6 h.
