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The novel enzyme polyenoic fatty acid isomerase (PFI) from the marine alga Ptilota filicina preferentially orients the substrate in the catalytic pocket with regard to the methyl terminus and that it likely reacts with the protonated form of the substrate. This was gleaned from the isomerization of a wide range of alternative substrates with PFI as catalyst. Further examination of the physiological of fatty acids in marine alga will result in a variety of novel enzymes with unique catalytic features.

A novel polyenoic fatty acid isomerase promotes the biosynthesis of conjugated triene-containing fatty acids from the red alga Ptilota filicina. The enzyme mediates the intermolecular transfer of the bis-allylic pro-S hydrogen from C11 and C8, in the substrate gamma-linolenate, to yield the conjugated triene. The primary protein in this purified enzyme has similar 58,119 Da subunits.

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Results of deuterium-labeling experiments that establish syn stereochemistry in both C-O bond-forming steps of the complex cyclization process catalyzed by the recombinant cyclase were reported. The results provided intriguing insight into the catalytic mechanism of the novel enzyme.

Tocochromanols are recognized for nutritional content, plant stress response, and seed longevity. Here we present a systems biological approach to characterize and develop predictive assays for genes affecting tocochromanol variation in barley. Major QTL, detected in three regions of a SNP linkage map, affected multiple tocochromanol forms. Candidate genes were identified through barley/rice orthology and sequenced in genotypes with disparate tocochromanol profiles. Gene-specific markers, designed based on observed polymorphism, mapped to the originating QTL, increasing R2 values at the respective loci. Polymorphism within promoter regions corresponded to motifs known to influence gene expression. Quantitative PCR analysis revealed a trend of increased expression in tissues grown at cold temperatures. These results demonstrate utility of a novel method for rapid gene identification and characterization, and provide a resource for efficient development of barley lines with improved tocochromanol profiles. [ABSTRACT FROM AUTHOR]

Phytochemicals are a rich source of chemoprevention agents but their effects on modulating the Wnt/β-catenin signaling pathway have remained largely uninvestigated. Aberrantly activated Wnt signaling can result in the abnormal stabilization of β-catenin, a key causative step in a broad spectrum of cancers. Here we report the modulation of lithium chlorideactivated canonical Wnt/β-catenin signaling by phytochemicals that have antioxidant, anti-inflammatory or chemopreventive properties. The compounds were first screened with a cervical cancer-derived stable Wnt signaling reporter HeLa cell line. Positive hits were subsequently evaluated for β-catenin degradation, suppression of β-catenin nuclear localization and down-regulation of downstream oncogenic targets of Wnt/β-catenin pathway. Our study shows a novel degradation path of β-catenin protein in HeLa cells by Avenanthramide 2p (a polyphenol) and Triptolide (a diterpene triepoxide), respectively from oats and a Chinese medicinal plant. The findings present Avenanthramide 2p as a potential chemopreventive dietary compound that merits further study using in vivo models of cancers; they also provide a new perspective on the mechanism of action of Triptolide. [ABSTRACT FROM AUTHOR]

The recently described enzyme, polyenoic fatty acid isomerase (PFI), from the marine alga Ptilota filicina J. Argardh has been analyzed with respect to its protein structure and an associated cofactor. The enzyme was purified to homogeneity (as judged by SDS–PAGE and silver staining). By sedimentation equilibrium ultracentrifugation the mass of the native enzyme was estimated to be 125 kDa. The N-terminal peptide sequence derived from this protein was used to isolate two very similar cDNA clones encoding novel 500-amino acid proteins, both with calculated molecular masses of 55.9 kDa and pIs of 4.87. The data predict translation of a preprotein containing a signal peptide of 21 amino acids that is removed during maturation. Deglycosylation assays demonstrate that native PFI from P. filicina is a glycoprotein. The purified protein is chromophoric with a flavin-like UV spectrum and sequence analysis reveals the presence of a flavin-binding motif near the mature N-terminus. Heterologous expression of active PFI in Arabidopsis, using one of the cDNA clones, was successful as evidenced by conversion of arachidonic acid to a conjugated triene in an in vitro assay of the transgenic plant tissues. [Copyright &y& Elsevier]

• Nutrients and avenanthramides are unevenly distributed within oat kernels. • Avenanthramides were most concentrated in outer layers of oat grains. • Avenanthramide contents and distribution within grains vary with oat varieties. • Pearled oats have lower contents of avenanthramides, protein, oil, and ash. • Pearled oats, however, contain higher concentrations of beta-glucan and starch. Hulled Reins and hulless Lamont oats were dehulled and/or sequentially abraded to produce ten pearling fines and corresponding pearled kernels. Contents of nutrients (protein, oil, starch, beta-glucan, ash and other carbohydrates) and avenanthramides (AVA) 2p, 2c, 2f, and 5p in processing fractions and starting grains were measured. Results show that distribution patterns of nutrients varied with individual nutrients, but those of AVAs varied with variety and individual AVAs. In both varieties, from the surface to inner endosperms, protein and oil increased then decreased; ash and other carbohydrates decreased; starch increased; and beta-glucan unchanged except for the surface area. In Lamont oat, the four AVAs decreased, but in Reins oat, AVA 2p decreased while 2c, 2f and 5p increased, then decreased. Compared to whole grain, pearled oats not only contained lower AVAs, protein, oil, ash, and other carbohydrates and higher beta-glucan and starch but also had a different AVA composition. [ABSTRACT FROM AUTHOR]