Polysaccharides, definition

Despite indications (from analytical data) that a monomethyl ether of a uronic acid occurs in the hydrolyzates of several polysaccharides, definite evidence for the presence of 4-O-methyl-D-glucuronic acid did not appear until 1948, when White found it in mesquite-gum hydroly-zate.14 Confirmation of its presence therein has since13 appeared, and it has also been found in the hydrolyzates from gum myrrh,6 aspen wood,14 and Eucalyptus regnans wood.16... 

Synonyms Anogeissus latifolia gum Ghatti gum Indian gum Clasafication Water-soluble polysaccharide Definition Gummy exudate from wounds in the batkof Anogeissus iaiifolia Properties Colorless to pale yel. solid almost odorless and tasteless partly sol. in water can be solubilized by autoclaving insol. in 90% alcohol... 

Classification Sulfated polysaccharide Definition Hydrocolloid obtained from various members of the Gigartinaceae or Solieriaceae families of the red seaweed, Rhodophyceae consists of sulfite esters of galactose and 3,6-an hydrogalactose copolymers Properties Yel. wh. powd., odorless, tasteless sol. in hot water, hot cone. NaCI sol n. insol. in oils and org. soivs. 

CAS 9000-69-5 EINECS/ELINCS 232-553-0 INS440 E440 Synonyms Citrus pectin Classification Polysaccharide Definition Purified carbohydrate prod, obtained from the dilute acid extract of the inner portion of the rind of citrus fruits or from apple pomace Properties Wh. to yel. powd. or syrupy cone., pract. odorless sol. in water insol. in alcohol, org. soivs. m.w. 30,000-100,000 Toxicology LD50 (subcut., mouse) 6400 mg/kg, low toxicity by subcut. route nonallergenic TSCA listed... 

Classification Polysaccharide Definition Water-sol. natural polymer produced by fermentation of the filamentous fungi, Sclerotium rofsii... 

Classification Complex polysaccharide Definition Pentose sugar Empiricai C5H10O5... 

Hemicellulose [9034-32-6] is the least utilized component of the biomass triad comprising cellulose (qv), lignin (qv), and hemiceUulose. The term was origiaated by Schulze (1) and is used here to distinguish the nonceUulosic polysaccharides of plant cell walls from those that are not part of the wall stmcture. Confusion arises because other hemicellulose definitions based on solvent extraction are often used in the Hterature (2—4). The term polyose is used in Europe to describe these nonceUulosic polysaccharides from wood, whereas hemicellulose is used to describe the alkaline extracts from commercial pulps (4). The quantity of hemicellulose in different sources varies considerably as shown in Table 1. 

Historically, dietary fiber referred to iasoluble plant cell wall material, primarily polysaccharides, not digested by the endogenous enzymes of the human digestive tract. This definition has been extended to iaclude other nondigestible polysaccharides, from plants and other sources, that are iacorporated iato processed foods. Cellulose [9004-34-6] (qv) is fibrous however, lignin [9005-53-2] (qv) and many other polysaccharides ia food do not have fiberlike stmctures (see also Carbohydrates). 

By far the majority of carbohydrate material in nature occurs in the form of polysaccharides. By our definition, polysaccharides include not only those substances composed only of glycosidically linked sugar residues but also molecules that contain polymeric saccharide structures linked via covalent bonds to amino acids, peptides, proteins, lipids, and other structures. 

The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules. 

Such structures do not conform to the original strict definition of polysaccharide but are generally classified as polysaccharides in current practice. 

Uronic acid definition, 51 nomenclature, 108-110 polysaccharide derivatives, 165... 

AG type II is most abundant in the heartwood of the genus Larix and occurs as minor, water-soluble components in softwoods. Certain tree parts of western larch (I. occidentalis) were reported to contain up to 35% AG [378]. The polysaccharide is located in the lumen of the tracheids and ray cells. Consequently, it is not a cell-wall component and, by definition, not a true hemicellulose. However, it is commonly classified as such in the field of wood and pulping research. This motivated us to include the larch AG in the review. 

C.d. spectroscopy is now being applied to more complicated polysaccharides. The 3-deoxy-D-man o-2-octulopyranosylonic acids found in Escherichia coli LP1092 have been definitely assigned the a-D configuration. The negative nir c.d. band exhibited by this polysaccharide correlates with the negative c.d. of methyl 3-deoxy-a-D-wianno-2-octulopyranosidonic acid rather than the positive c.d. band exhibited by methyl 3-deoxy-)3-D-/ a/ino-2-octulopyranosidonic acid. 

Carbohydrates are characterized by the presence of polyhydroxylic aldehyde or polyhydroxy-lic ketone structures or polymers made of such units. Sugars and polysaccharides have definite... 

The regulations prescribe the energy values to be used as in Table 3. There are agreed values for some other materials. The synthetic dextrose polymer poly dextrose is accepted to be only 1 kcal g 1 (or 4 kJ g 1) even though it would otherwise fall within the definition of a carbohydrate. The accepted value for gum acacia, a polysaccharide obtained from trees of the species Acacia Senegal and closely related species, is 2 kcal g 1 (or 8 kJ g-1). 

Needless to say, there is a definite possibility that, if reactions as just described participate in the transformations of polyuronide polysaccharides, enzymatic control of these may exist by systems leading to the oxidation of ascorbic acid or producing peroxide-type intermediaries. 

On treatment with periodatd ion, straw and beechwood xylan oxidize rapidly.104 As with other polysaccharides, the oxidation comes to a more definite end point in solutions which are buffered to pH 4-5. While somewhat more than the theoretical amount of periodate ion is consumed, the reaction apparently proceeds uniformly with oxidative cleavage of the 2,3 carbon bond to produce the structure indicated in Figure 4. In the course of the reaction the xylan passes into solution. The optical rotation of the oxidized product is surprisingly high (co. 100°). 

Matthijs, N., Perrin, C., Maftouh, M., Massart, D.L., Vander Heyden, Y. Definition and system implementation of strategies for method development of chiral separations in normal- or reversed-phase liquid chromatography using polysaccharide-based stationary phases. 7. Chromatogr. A 2004, 1041, 119-133. 

Dietary fibre was defined by Hugh TroweU as the plant polysaccharides and lignin which are resistant to hydrolysis by the digestive enzymes of humans . This definition lacks chemical precision, because non-flbrous pectins and gums are also present. The term nonstarch polysaccharide (NSP) is often preferred, although the term dietary fibre still persists. Unfortunately, NSP is also not satisfactory since some starch, known as resistant or par-... 

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