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Xylan Hardwood
Xylan (; ) (CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is the third most abundant biopolymer on Earth, after cellulose and chitin. Composition Xylans are polysaccharides made up of β-1,4-linked xylose (a pentose sugar) residues with side branches of α-arabinofuranose and/or α-glucuronic acids. On the basis of substituted groups xylan can be categorized into three classes i) glucuronoxylan (GX) ii) neutral arabinoxylan (AX) and iii) glucuronoarabinoxylan (GAX). In some cases contribute to cross-linking of cellulose microfibrils and lignin through ferulic acid residues. Occurrence Plant cell structure Xylans play an important role in the integrity of the plant cell wall and increase cell wall recalcitrance to enzymatic digestion; thus, they help plants to defend against herbivores and pathogens (biotic stress). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylan Hardwood
Xylan (; ) (CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is the third most abundant biopolymer on Earth, after cellulose and chitin. Composition Xylans are polysaccharides made up of β-1,4-linked xylose (a pentose sugar) residues with side branches of α-arabinofuranose and/or α-glucuronic acids. On the basis of substituted groups xylan can be categorized into three classes i) glucuronoxylan (GX) ii) neutral arabinoxylan (AX) and iii) glucuronoarabinoxylan (GAX). In some cases contribute to cross-linking of cellulose microfibrils and lignin through ferulic acid residues. Occurrence Plant cell structure Xylans play an important role in the integrity of the plant cell wall and increase cell wall recalcitrance to enzymatic digestion; thus, they help plants to defend against herbivores and pathogens (biotic stress). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Catalysis
Enzyme catalysis is the increase in the rate of a process by a biological molecule, an "enzyme". Most enzymes are proteins, and most such processes are chemical reactions. Within the enzyme, generally catalysis occurs at a localized site, called the active site. Most enzymes are made predominantly of proteins, either a single protein chain or many such chains in a multi-subunit complex. Enzymes often also incorporate non-protein components, such as metal ions or specialized organic molecules known as cofactor (e.g. adenosine triphosphate). Many cofactors are vitamins, and their role as vitamins is directly linked to their use in the catalysis of biological process within metabolism. Catalysis of biochemical reactions in the cell is vital since many but not all metabolically essential reactions have very low rates when uncatalysed. One driver of protein evolution is the optimization of such catalytic activities, although only the most crucial enzymes operate near catalytic e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prebiotic (nutrition)
Prebiotics are compounds in food that induce the growth or activity of beneficial microorganisms such as bacteria and fungi. The most common example is in the gastrointestinal tract, where prebiotics can alter the composition of organisms in the gut microbiome. Dietary prebiotics are typically nondigestible fiber compounds that pass undigested through the upper part of the gastrointestinal tract and stimulate the growth or activity of advantageous bacteria in the colon by acting as substrates for them. They were first identified and named by Marcel Roberfroid in 1995. Depending on the jurisdiction, they may have regulatory scrutiny as food additives for the health claims made for marketing purposes. Common prebiotics used in food manufacturing include beta-glucan from oats and inulin from chicory root. Definition The definition of prebiotics and the food ingredients that can fall under this classification, has evolved since its first definition in 1995. In its earliest defi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylooligosaccharide
Xylooligosaccharides (XOS) are polymers of the sugar xylose. They are produced from the xylan fraction in plant fiber. Their C5 (where C is a quantity of carbon atoms in each monomer) structure is fundamentally different from other prebiotics, which are based upon C6 sugars. Xylooligosaccharides have been commercially available since the 1980s, originally produced by Suntory in Japan. They have more recently become more widely available commercially, as technologies have advanced and production costs have fallen. Some enzymes from yeast can exclusively convert xylan into only xylooligosaccharides-DP-3 to 7. Xylooligosaccharides act as a prebiotic, selectively feeding beneficial bacteria such as bifidobacteria and lactobacilli within the digestive tract. A large number of clinical trials have been conducted with XOS, demonstrating a variety of health benefits, including improvements in blood sugars and lipids, digestive health benefits, laxation, and beneficial changes to immune ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antinutrient
Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. Nutrition studies focus on antinutrients commonly found in food sources and beverages. Antinutrients may take the form of drugs, chemicals that naturally occur in food sources, proteins, or overconsumption of nutrients themselves. Antinutrients may act by binding to vitamins and minerals, preventing their uptake, or inhibiting enzymes. Throughout history, humans have bred crops to reduce antinutrients, and cooking processes have developed to remove them from raw food materials and increase nutrient bioavailability, notably in staple foods such as cassava. Mechanisms Preventing mineral uptake Phytic acid has a strong binding affinity to minerals such as calcium, magnesium, iron, copper, and zinc. This results in precipitation, making the minerals unavailable for absorption in the intestines. Phytic acids are common in the hulls of nuts, seeds, and grains and of great importance in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Algae
Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority of species (6,793) are found in the Florideophyceae (class), and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats but relatively rare in freshwaters. Approximately 5% of red algae species occur in freshwater environments, with greater concentrations found in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, there are no terrestrial species, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity. The red algae form a distinct group characterized by having eukaryotic cells without flagella and centrioles, chloroplasts that l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bryopsis
''Bryopsis'' is a genus of marine green algae in the family Bryopsidaceae. It is frequently a pest in aquariums, where it is commonly referred to as hair algae. Introduction ''Bryopsis''/ˌbɹaɪˈɑpsɪs/ is a genus of macroscopic, siphonous marine green algae that is made up of units of single tubular filaments. Species in this genus can form dense tufts up to 40 cm in height (Fong et al., 2019; Giovagnetti et al., 2018). Each cell is made of up an erect thallus that is often branched into pinnules (Green, 1960). Approximately 60 species have been identified in this genus since its initial discovery in 1809 (J. V. . Lamouroux, 1809). The ecological success of ''Bryopsis'' has also been attributed to its associations with endophytic bacteria that reside in the cytoplasm of their cells (Hollants, Leliaert, Verbruggen, Willems, & De Clerck, 2013). Species in this genus are known to be pests in aquariums and associated with green tides due to macroalgal blooms (Han, Li, Wei, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codium
''Codium'' is a genus of seaweed in the Chlorophyta of the order Bryopsidales. Paul Silva was an expert on the genus ''Codium'' taxonomy at the University of California, Berkeley. There are about 50 species worldwide. Description The genus has thalli of two forms, either erect or prostrate. The erect plants are dichotomously branched to long with branches forming a compact spongy structure, not calcareous. The final branches form a surface layer of close palisade cortex of utricles. The non-erect species form either a prostrate or globular thallus with a velvet-like surface, the final branches forming a close cortex of utricles. Distribution Ireland Two of these species are very rare in Ireland. '' Codium adhaerens'' has been recorded from a few sites on the west coast and from Tory Island on the north coast in County Donegal. In 1837 it was found in Church Bay in County Antrim,Morton,O. 1994. ''Marine Algae of Northern Ireland.'' Ulster Museum. but has not been found the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Algae
The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as sister of the Zygnematophyceae. Since the realization that the Embryophytes emerged within the green algae, some authors are starting to properly include them. The completed clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid and filamentous forms, and macroscopic, multicellular seaweeds. There are about 22,000 species of green algae. Many species live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds. A few other organi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabinose
Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. For biosynthetic reasons, most saccharides are almost always more abundant in nature as the "D"-form, or structurally analogous to D-glyceraldehyde.The D/L nomenclature does not refer to the molecule's optical rotation properties but to its structural analogy to glyceraldehyde. However, L-arabinose is in fact more common than D-arabinose in nature and is found in nature as a component of biopolymers such as hemicellulose and pectin. The L-arabinose operon, also known as the araBAD operon, has been the subject of much biomolecular research. The operon directs the catabolism of arabinose in ''E. coli'', and it is dynamically activated in the presence of arabinose and the absence of glucose. A classic method for the organic synthesis of arabinose from glucose is the Wohl degradation. : Etymology Arabinose gets its name from gum arabic, from which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
