Wheat arabinoxylans: Exploiting variation in amount …
Water-soluble arabinoxylans from wheat flour were purified and fractionated by graded ethanol precipitation. Six fractions were obtained at 20% (F20), 30% (F30), 40% (F40), 50% (F50), 60% (F60), and 70% (F70) saturation with ethanol. Neutral sugars and 1H NMR analyses revealed differences in structural characteristics. The Ara/Xyl ratio and the amount of Xyl residues disubstituted increased with ethanol concentration. Ferulic acid content was higher in fractions precipitated at low ethanol percentage. Fractions were refractionated by SEC, leading to 46 subfractions with low polydispersity index. Substitution degree was apparently linearly related to the amount of disubstituted Xyl. Macromolecular characteristics (w, [η], G, , ν) determined by multiangle laser light scattering and viscosimetry were similar among all fractions. A rather flexible conformation was determined for the arabinoxylans, in conflict with the admitted rodlike conformation. The substitution degree had no influence on the conformation or on the rigidity of the polymers. Evidence for the presence of ferulic acid dimers in the water-soluble arabinoxylans is provided, which probably explains the unexpected conformation and macromolecular characteristics.
Read "Wheat arabinoxylans: Exploiting variation in amount and ..
The selection of appropriate acidifiers plays an important role in its usage as an alternate to antibiotics and the pKa value in range of 3-5 was found optimal. The pKa values of different s were presented in .
This paper summarises recent knowledge on the structure and physicochemical properties of AX including variation between cultivars and tissues, methods for analysis and screening, biosynthetic mechanisms and approaches to identifying key genes.
water-soluble wheat arabinoxylans--effects of ..
At the moment we are predominantly working on understanding the biosynthesis of diverse variants of xylan and glucomannan in different plants. Both xylan and glucomannan are hemicellulosic components of the plant cell wall that are synthesized in the Golgi apparatus. In general, our research focuses on understanding how the polysaccharides are synthesized, what their structure is and how the structure relates to function. Recently published work on xylan biosynthesis and glucomannan biosynthesis exemplifies our approach of combining reverse genetics, cell biology and biochemical methods to analyse protein function and polysaccharide structure. The complexity of polysaccharide structures and their analysis are exemplified by our work on the structure of arabinogalactans.
arabinoxylan (HMW-AX), isolated from wheat ..
Arabinoxylans (AXs) are major components of plant cell walls in bread wheat and are important in bread-making and starch extraction. Furthermore, arabinoxylans are components of soluble dietary fibre that has potential health-promoting effects in human nutrition. Despite their high value for human health, few studies have been carried out on the genetics of AX content in durum wheat.
Intracellular feruloylation of arabinoxylan in wheat: ..
For all of the candidate genes that have annotations, an in silico gene expression analysis was conducted to provide further evidence of their potential involvement in the AX biosynthetic pathway. Exploiting the PLEXdb database , the expression data from the Wheat 61k GeneChip was investigated to predict the genes’ impact on the final AX content. In particular, we analysed the transcription pattern variation during different wheat developmental stages (Experiment TA3), focusing on the transcript level in caryopsis at 3–5 days after pollination (DAP), embryos at 22 DAP, and endosperm at 22 DAP (). In total seven of the gene sequences showed log intensity values higher than 8 (with RMA normalization), and these corresponded to the queries associated with TaUGT1, cisZog2B, Utg12887, Gsl12, all of which encode glycosyl transferase enzymes . The data support the hypothesis of correlation between the transcript levels and the AX content, in fact, abundant transcripts encoding synthetic enzymes give the success in identifying candidate genes for cell wall synthesis from transcriptomics.