Functional Properties of Carbohydrate Dudsadee Uttapap
Carbohydrate Chemical Properties Physical Properties Functional Properties
Carbohydrate functions Energy sources (glucose/glycogen) Structural elements cell wall (plants, bacteria) connective tissues adhesion between cells
Dermatan sulfate composed of L-iduronate (many are sulfated) + GalNAc-4-sulfate linkages is (1, 3)
The most abundant heteropolysaccharides in the body are the glycosaminoglycans (GAGs). These molecules are long unbranched polysaccharides containing a repeating disaccharide unit. The disaccharide units contain either of two modified sugars--- N-acetylgalactosamine (GalNAc) or N-acetylglucosamine (GlcNAc) and a uronic acid such as glucuronate or iduronate. GAGs are highly negatively charged molecules, with extended conformation that imparts high viscosity to the solution. GAGs are located primarily on the surface of cells or in the extracellular matrix (ECM). Along with the high viscosity of GAGs comes low compressibility, which makes these molecules ideal for a lubricating fluid in the joints. At the same time, their rigidity provides structural integrity to cells and provides passageways between cells, allowing for cell migration. The specific GAGs of physiological significance are hyaluronic acid, dermatan sulfate, chondroitin sulfate, heparin, heparan sulfate, and keratan sulfate.
Characteristics of GAGs Characteristics of GAGs
Peptidoglycan two sugars are N-acetyl glucosamine (NAG) and N-acetyl muramic acid (NAM).
Monoosaccharide Aldose 6C: glucose, mannose 5C: ribose, xylose, arabinose 4C: erythrose, threose 3C: glyceraldehyde Ketose 6C: fructose, sorbose 5C: erythropentulose
Galactose Glucose Ribose Mannose
Oligosaccharide -starch oligosaccharide; maltose, stachyose -cellulose: cellobiose -sucrose, lactose, trehalose -cyclodextrin (6C,7C,8C) -fructooligosaccharide (GF2,GF3,GF4) -coupling sugar (Gn-G-F)
Cyclodextrin Monomer: Glucose Bonding: -1,4
Fructans are probably the most abundant storage carbohydrate in plants next to starch and sucrose. Fructans are linear or branched polymers of mostly ß-fructosyl-fructose linkages. Unlike sucrose they are synthesized and stored in vacuoles and can accumulate in the stems, bulbs and tubers of a number of plants
Fructooligosaccharides are a fruit derived sugar. These promote the grown of bifidobacteria in the gut. Bifidobacteria produce a natural antibiotic against E.Coli 0157:H7 AND stroptococcus. There are fewer bifidobacteria in the elderly (who also tend to eat less fruit). So, it is the elderly who mostly die from this deadly E.Coli infection.
Sources Microbial: xanthan, gellan, dextran Seaweed; carrageenan, agar, alginate Plant: gum arabic, guar gum, pectin, cellulose, starch, konjac Animal: chitin
Cellulose Monomer: glucose Bonding: -1,4 Carboxymethyl cellulose
-Glucan Monomer: Glucose Bonding: -1,4/-1,3 The ß-1,3 glucan, callose, also similar to cellulose, is an important polymeric component of sieve plates of phloem tubes. Callose is also produced during wound healing of damaged plant tissues
Chitin Monomer: acetylglucosamine Bonding: -1,4
Agarose Monomer: D-galactose/3,6-anhydro-L-galactose Bonding: -1,3/-1,4
Konjac (glucomannan) Monomer: glucose, mannose Bonding: -1,4
Alginate G M G, M Monomer:-mannuronic acid (M) -L-guluronic acid (G) Bonding: -1,4/-1,4
Pectin Monomer: D-galacturonic acid, L-rhamnose Others: D-galactose, D-xylose, D-arabinose short side chain) Bonding: -1,4
Carrageenan Monomer: D-galactose (anhydro/sulfate) Bonding: -1,4/-1,3
kappa iota lambda
Xanthan Monomer: backbone glucose (as cellulose) side chain mannose/glucuronic acid Bonding: -1,4/-1,2/-1,3
Dextran Dextran is an α-D-1,6-glucose-linked glucan with side-chains 1-3 linked to the backbone units of the Dextran biopolymer. The degree of branching is approximately 5%. The branches are mostly 1-2 glucose units long. Dextran can be obtained from fermentation of sucrose-containing media by Leuconostoc mesenteroides B512F.
Seed Gum Locust bean gum Monomer: galactose, mannose (galactomannan) Bonding: -1,4/-1,6 (branch)
Guar gum Monomer: galactose, mannose (galactomannan) Bonding: -1,6/-1,4
Tamatind gum, the heavily substitured natural cellulosic Exhibits a very low level of mixed gelling interaction with other polysaccharides.
Plant exudate Gum karaya Gum ghatti Gum Tragacanth Gum arabic
Gum Arabic -complex heteropolysaccharide -low viscosity
Functional properties of carbohydrate Food products Nonfood products Structural-function relationship Molecular size Molecular arrangement Chemical composition Functional group