Release of Ferulic Acid Esters From Barley Aleurone. I. Time Course of Gibberellic-Acid-Induced Release From Isolated Layers

1985 ◽  
Vol 12 (3) ◽  
pp. 297 ◽  
Author(s):  
F Gubler ◽  
AE Ashford
Keyword(s):  
Gibberellic Acid ◽  
Ferulic Acid ◽  
Cell Walls ◽  
Time Course ◽  
Free Acid ◽  
Hordeum Vulgare L ◽  
Barley Aleurone ◽  
Ester Linkage ◽  
Hydrolysis Of ◽  
Acid Esters

Removal of ferulic acid from barley aleurone cell walls is closely correlated with wall hydrolysis. The ferulic acid content of isolated aleurone layers (Hordeum vulgare L. cv. Himalaya) falls progressively during incubation with gibberellic acid (GA3), to about one-third of the original content, by 72 h. At the same time an equivalent amount accumulates in the incubation medium, not as the free acid but still esterified to other components. The data show that there is no modification of the feruloyl group, or hydrolysis of the ester linkage prior to removal from the tissue, and therefore the GA3-induced aleurone peroxidases and esterases are not directly involved.

Gibberellic acid, ?-1,3-glucanase and the cell walls of barley aleurone layers

Planta ◽  
1970 ◽  
Vol 92 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Lincoln Taiz ◽  
Russell L. Jones
Keyword(s):  
Gibberellic Acid ◽  
Cell Walls ◽  
Barley Aleurone

Sorting out theLeMANs: endo-β-mannanase genes and their encoded proteins in tomato

2007 ◽  
Vol 17 (3) ◽  
pp. 143-154 ◽  
Author(s):  
Xuemei Gong ◽  
J. Derek Bewley
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Gibberellic Acid ◽  
Cell Walls ◽  
Plant Cell Walls ◽  
Tomato Seeds ◽  
C Terminus ◽  
Inactive Form ◽  
Genes Encoding ◽  
Hydrolysis Of

AbstractEndo-β-mannanase (EC 3.2.1.78) is involved in the hydrolysis of mannan-type polysaccharides that are present in plant cell walls, especially those of the seed endosperm. The genes encoding the endo-β-mannanases have been studied extensively in tomato (Solanum lycopersicum), and five genes (LeMAN1,LeMAN2,LeMAN3,LeMAN4andLeMAN5) and/or their products have been isolated and characterized.LeMAN1,LeMAN2andLeMAN3are expressed in tomato seeds,LeMAN4in the fruit andLeMAN5in the flower.LeMAN5andLeMAN2are now considered to be the same gene, and the former is re-designated asLeMAN2*. Transcripts ofLeMANs1, 2and3are detected only in the endosperm of tomato seeds, and their synthesis is promoted by gibberellic acid.LeMAN4, in the fruit, occurs asLeMAN4aandLeMAN4igenes that encode an active or inactive form of endo-β-mannanase, respectively.LeMAN1–4 enzymes encoded by these genes share 80% similarity in amino acid sequence. In tomato, the leucine amino acid present near to the C-terminus of the endo-β-mannanase is the most important for achieving full activity of the enzyme.

scholarly journals Improved analysis of arabinoxylan-bound hydroxycinnamate conjugates in grass cell walls

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Alexis Eugene ◽  
Catherine Lapierre ◽  
John Ralph
Keyword(s):  
Cell Wall ◽  
Ferulic Acid ◽  
Cell Walls ◽  
Ester Hydrolysis ◽  
Industrial Processes ◽  
Coupling Reactions ◽  
Coumaric Acid ◽  
Orthogonal Method ◽  
Radical Coupling ◽  
Hydrolysis Of

Abstract Background Arabinoxylan in grass cell walls is acylated to varying extents by ferulate and p-coumarate at the 5-hydroxy position of arabinosyl residues branching off the xylan backbone. Some of these hydroxycinnamate units may then become involved in cell wall radical coupling reactions, resulting in ether and other linkages amongst themselves or to monolignols or oligolignols, thereby crosslinking arabinoxylan chains with each other and/or with lignin polymers. This crosslinking is assumed to increase the strength of the cell wall, and impedes the utilization of grass biomass in natural and industrial processes. A method for quantifying the degree of acylation in various grass tissues is, therefore, essential. We sought to reduce the incidence of hydroxycinnamate ester hydrolysis in our recently introduced method by utilizing more anhydrous conditions. Results The improved methanolysis method minimizes the undesirable ester-cleavage of arabinose from ferulate and p-coumarate esters, and from diferulate dehydrodimers, and produces more methanolysis vs. hydrolysis of xylan-arabinosides, improving the yields of the desired feruloylated and p-coumaroylated methyl arabinosides and their diferulate analogs. Free ferulate and p-coumarate produced by ester-cleavage were reduced by 78% and 68%, respectively, and 21% and 39% more feruloyl and p-coumaroyl methyl arabinosides were detected in the more anhydrous method. The new protocol resulted in an estimated 56% less combined diferulate isomers in which only one acylated arabinosyl unit remained, and 170% more combined diferulate isomers conjugated to two arabinosyl units. Conclusions Overall, the new protocol for mild acidolysis of grass cell walls is both recovering more ferulate- and p-coumarate-arabinose conjugates from the arabinoxylan and cleaving less of them down to free ferulic acid, p-coumaric acid, and dehydrodiferulates with just one arabinosyl ester. This cleaner method, especially when coupled with the orthogonal method for measuring monolignol hydroxycinnamate conjugates that have been incorporated into lignin, provides an enhanced tool to measure the extent of crosslinking in grass arabinoxylan chains, assisting in identification of useful grasses for biomass applications.

Barley aleurone xylanase: its biosynthesis and possible role

1989 ◽  
Vol 67 (2) ◽  
pp. 297-302 ◽  
Author(s):  
E. Benjavongkulchai ◽  
M. S. Spencer
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
De Novo ◽  
Xylanase Activity ◽  
Hordeum Vulgare L ◽  
Aleurone Cells ◽  
Initial Release ◽  
Barley Aleurone ◽  
Scanning Electron

The synthesis of barley (Hordeum vulgare L. cv. Himalaya) aleurone xylanase was found to be dependent on both gibberellic acid (GA3) and Ca2+, but inhibited by cycloheximide and cordycepin. Studies using density labeling of barley aleurone layers showed that xylanase was synthetized de novo in response to GA3 and Ca2+. Neither GA3 nor Ca2+ alone induced a large increase in xylanase activity. The concentration of Ca2+ required for maximum xylanase induction was 5 – 40 mM. Xylanase activity was found to develop simultaneously with that of α-amylase in the incubation medium during the first 24 h of incubation with GA3. A critical point with respect to the role of xylanase is the extent of its activity by the time of the initial release of α-amylase. The release of α-amylase into the medium was detectable at 6 h. From 2 to 6% of the cell wall was hydrolysed by xylanase after incubation for 6 h, which was probably sufficient to permit the release of α-amylase. Scanning electron microscopy showed that the purified barley aleurone xylanase hydrolysed the cell walls of barley aleurone layers in the absence of GA3. It is likely that xylanase plays an important role in the release of enzymes from aleurone cells.

Studies on the mechanism of acute inhibition of thyroglobulin hydrolysis by iodine

1985 ◽  
Vol 108 (4) ◽  
pp. 511-517 ◽  
Author(s):  
Nandalal Bagchi ◽  
Birdie Shivers ◽  
Thomas R. Brown
Keyword(s):  
Time Course ◽  
Period 2 ◽  
Iodotyrosine Deiodinase ◽  
Rate Of Hydrolysis ◽  
Underlying Mechanisms ◽  
Excess Iodide ◽  
Sites Of Action ◽  
Hydrolysis Of

Abstract. Iodine in excess is known to acutely inhibit thyroidal secretion. In the present study we have characterized the time course of the iodine effect in vitro and investigated the underlying mechanisms. Labelled thyroid glands were cultured in vitro in medium containing mononitrotyrosine, an inhibitor of iodotyrosine deiodinase. The rate of hydrolysis of labelled thyroglobulin was measured as the proportion of labelled iodotyrosines and iodothyronines recovered at the end of culture and was used as an index of thyroidal secretion. Thyrotrophin (TSH) administered in vivo acutely stimulated the rate of thyroglobulin hydrolysis. Addition of Nal to the culture medium acutely inhibited both basal and TSH-stimulated thyroglobulin hydrolysis. The effect of iodide was demonstrable after 2 h, maximal after 6 h and was not reversible upon removal of iodide. Iodide abolished the dibutyryl cAMP induced stimulation of thyroglobulin hydrolysis. Iodide required organic binding of iodine for its effect but new protein or RNA synthesis was not necessary. The inhibitory effects of iodide and lysosomotrophic agents such as NH4C1 and chloroquin on thyroglobulin hydrolysis were additive suggesting different sites of action. Iodide added in vitro altered the distribution of label in prelabelled thyroglobulin in a way that suggested increased coupling in the thyroglobulin molecule. These data indicate that 1) the iodide effect occurs progressively over a 6 h period, 2) continued presence of iodide is not necessary once the inhibition is established, 3) iodide exerts its action primarily at a post cAMP, prelysosomal site and 4) the effect requires organic binding of iodine, but not new RNA or protein synthesis. Our data are consistent with the hypothesis that excess iodide acutely inhibits thyroglobulin hydrolysis by increasing the resistance of thyroglobulin to proteolytic degradation through increased iodination and coupling.

scholarly journals Optimizing Chitin Depolymerization by Lysozyme to Long-Chain Oligosaccharides

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 320
Author(s):  
Arnaud Masselin ◽  
Antoine Rousseau ◽  
Stéphanie Pradeau ◽  
Laure Fort ◽  
Rodolphe Gueret ◽  
...  
Keyword(s):  
Time Course ◽  
Water Soluble ◽  
Organic Fertilizers ◽  
Symbiotic Associations ◽  
Egg White Lysozyme ◽  
Hen Egg White ◽  
Ecological Transition ◽  
Optimized Conditions ◽  
Hydrolysis Of ◽  
Long Chain

Chitin oligosaccharides (COs) hold high promise as organic fertilizers in the ongoing agro-ecological transition. Short- and long-chain COs can contribute to the establishment of symbiotic associations between plants and microorganisms, facilitating the uptake of soil nutrients by host plants. Long-chain COs trigger plant innate immunity. A fine investigation of these different signaling pathways requires improving the access to high-purity COs. Here, we used the response surface methodology to optimize the production of COs by enzymatic hydrolysis of water-soluble chitin (WSC) with hen egg-white lysozyme. The influence of WSC concentration, its acetylation degree, and the reaction time course were modelled using a Box–Behnken design. Under optimized conditions, water-soluble COs up to the nonasaccharide were formed in 51% yield and purified to homogeneity. This straightforward approach opens new avenues to determine the complex roles of COs in plants.

scholarly journals Evidence for the Formation of Hippuryl Chymotrypsin during the Hydrolysis of Hippuric Acid Esters

1963 ◽  
Vol 238 (5) ◽  
pp. 1718-1723 ◽  
Author(s):  
Richard M. Epand ◽  
Irwin B. Wilson
Keyword(s):  
Hippuric Acid ◽  
Hydrolysis Of ◽  
Acid Esters
Sign in / Sign up

Export Citation Format

Share Document