3D structure of cellulose. Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4

Polysaccharides are relatively complex carbohydrates. Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most They are polymers made up of many monosaccharides joined together by glycosidic bonds. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Monosaccharides (from Greek monos: single sacchar: sugar are the most basic unit of Carbohydrates They consist of one sugar and In Chemistry, a glycosidic bond is a certain type of Functional group that joins a Carbohydrate (sugar molecule to another which may be another carbohydrate They are therefore very large, often branched, macromolecules. The term macromolecule by definition implies "large Molecule " They tend to be amorphous, insoluble in water, and have no sweet taste. An amorphous solid is a Solid in which there is no Long-range order of the positions of the Atoms (Solids in which there is long-range atomic order are Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Sweet is one of the five Basic tastes and is almost universally regarded as a pleasurable experience

When all the monosaccharides in a polysaccharide are the same type the polysaccharide is called a homopolysaccharide, but when more than one type of monosaccharide is present they are called heteropolysaccharides.

Examples include storage polysaccharides such as starch and glycogen and structural polysaccharides such as cellulose and chitin. Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide Glycogen is a Polysaccharide of Glucose (Glc which functions as the secondary short term energy storage in Animal cells Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine

Polysaccharides have a general formula of C_n(H₂O)_n-1 where n is usually a large number between 200 and 2500. Considering that the repeating units in the polymer backbone are often six-carbon monosaccharides, the general formula can also be represented as (C₆H₁₀O₅)_n where n={40. . . 3000}.

Storage polysaccharides

Starches

Starches are glucose polymers in which glucopyranose units are bonded by alpha-linkages. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. It is made up of a mixture of Amylose and Amylopectin. Amylose ( CAS # 9005-82-7 is a planar Polymer of Glucose linked mainly by α(1→4 bonds Amylopectin ( CAS # 9037-22-3 is a highly branched Polymer of Glucose found in plants Amylose consists of a linear chain of several hundred glucose molecules and Amylopectin is a branched molecule made of several thousand glucose units.

Starches are insoluble in water. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Water is a common Chemical substance that is essential for the survival of all known forms of Life. They can be digested by hydrolysis, catalyzed by enzymes called amylases, which can break the alpha-linkages (glycosidic bonds). Amylase is an Enzyme that breaks Starch down into Sugar. Amylase is present in human Saliva, where it begins the chemical process Humans and other animals have amylases, so they can digest starches. Potato, rice, wheat, and corn are major sources of starch in the human diet. The potato is a Starchy Tuberous crop Vegetable from the perennial Solanum tuberosum of the Solanaceae Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many Wheat ( Triticum spp is a worldwide cultivated grass from the Levant area of the Middle East. Maize (ˈmeɪz ( Zea mays L. ssp mays) known as corn in some countries is a cereal grain domesticated in Mesoamerica

Glycogen

Glycogen is a polysaccharide that is found in animals and is composed of a branched chain of glucose residues. Glycogen is a Polysaccharide of Glucose (Glc which functions as the secondary short term energy storage in Animal cells It is stored in liver and muscles.

Structural polysaccharides

Cellulose

The structural component of plants are formed primarily from cellulose. Plants are living Organisms belonging to the kingdom Plantae. Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose. Lignin or lignen is a complex Chemical compound most commonly derived from Wood and an integral part of the secondary Cell walls of Plants Paper is thin material mainly used for writing upon printing upon or packaging Cotton is a soft staple Fibre that grows around the seeds of the cotton plant ( Gossypium sp Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Humans and many other animals lack an enzyme to break the beta-linkages, so they do not digest cellulose. Certain animals can digest cellulose, because bacteria possessing the enzyme are present in their gut. The classic example is the termite. The termites are a group of Social Insects usually classified at the taxonomic rank of order Isoptera (but see also taxonomy

Acidic polysaccharides

Acidic polysaccharides are polysaccharides that contain carboxyl groups, phosphate groups and/or sulfuric ester groups. Carboxyl group or CO2H is a Functional group present in Amino acids and Carboxylic acids Its structure is composed of one carbon atom attached Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Esters are a class of Chemical compounds and Functional groups Esters consist of an inorganic or organic Acid in which at least

Bacterial capsule polysaccharides

Pathogenic bacteria commonly produce a thick, mucous-like, layer of polysaccharide. Pathogenic bacteria are Bacteria that cause Infectious diseases. This "capsule" cloaks antigenic proteins on the bacterial surface that would otherwise provoke an immune response and thereby lead to the destruction of the bacteria. An antigen (from antibody-generating) or immunogen is a substance that prompts the generation of Antibodies and can cause an immune response Capsular polysaccharides are water soluble, commonly acidic, and have molecular weights on the order of 100-1000 kDa. The molecular mass (abbreviated m of a substance, more commonly referred to as molecular weight and abbreviated as MW, is the Mass of one The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express They are linear and consist of regularly repeating subunits of one ~ six monosaccharides. There is enormous structural diversity; nearly two hundred different polysaccharides are produced by E. coli alone. Mixtures of capsular polysaccharides, either conjugated or native are used as vaccines. A conjugate vaccine is created by covalently attaching a poor Antigen to a Carrier protein, thereby conferring the immunological attributes of the carrier on the attached A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease

Bacteria and many other microbes, including fungi and algae, often secrete polysaccharides as an evolutionary adaptation to help them adhere to surfaces and to prevent them from drying out. Humans have developed some of these polysaccharides into useful products, including xanthan gum, dextran, gellan gum, and pullulan. Xanthan gum is a Polysaccharide used as a Food additive and Rheology modifier. Dextran is a complex branched Glucan ( Polysaccharide) made of many Glucose molecules joined into chains of varying lengths (from 10 to 150 kilodaltons Pullulan is a Polysaccharide Polymer consisting of Maltotriose units also known as α-14-;α-16- Glucan.

Cell-surface polysaccharides play diverse roles in the bacterial "lifestyle". They serve as a barrier between the cell wall and the environment, mediate host-pathogen interactions, and form structural components of biofilms. A cell wall is a tough flexible and sometimes fairly rigid layer surrounding a cell, located external to the Cell membrane, which provides the cell with structural A biofilm is a structured community of Microorganisms encapsulated within a self-developed polymeric matrix and adherent to a living or inert surface These polysaccharides are synthesized from nucleotide-activated precursors and, in most cases, all the enzymes necessary for biosynthesis, assembly and transport of the completed polymer are encoded by genes organized in dedicated clusters within the genome of the organism. Lipopolysaccharide is one of the most important cell-surface polysaccharides, as it plays a key structural role in outer membrane integrity, as well as being an important mediator of host-pathogen interactions. Lipopolysaccharides ( LPS) are large Molecules consisting of a Lipid and a Polysaccharide joined by a Covalent bond; they are found The genetics for the biosynthesis of the so-called A-band (homopolymeric) and B-band (heteropolymeric) O antigens have been clearly defined, and a lot of progress has been made toward understanding the biochemical pathways of their biosynthesis. The exopolysaccharide alginate is a linear copolymer of ß-1,4-linked D-mannuronic acid and L-guluronic acid residues, and is responsible for the mucoid phenotype of late-stage cystic fibrosis disease. The pel and psl loci are two recently discovered gene clusters that also encode exopolysaccharides found to be important for biofilm formation. Rhamnolipid is a biosurfactant whose production is tightly regulated at the transcriptional level, but the precise role that it plays in disease is not well understood at present. Protein glycosylation, particularly of pilin and flagellin, is a recent focus of research by several groups and it has been shown to be important for adhesion and invasion during bacterial infection. Pilin refers to a class of fibrous Proteins that are found in Pilus structures in Bacteria. Flagellin is a Protein that arranges itself in a hollow cylinder to form the filament in Bacterial Flagellum. ^[1]

See also

• Polysaccharide encapsulated bacteria
• Glycans

References

Sutherland, I. Polysaccharide encapsulated bacteria, frequently referred to simply as encapsulated bacteria and less precisely called encapsulated organisms, are a group The term glycan refers to a Polysaccharide or Oligosaccharide. W. (2002) Polysaccharides from Microorganisms, Plants and Animals, in: Biopolymers, Volume 5, Polysaccharides I: Polysaccharides from Prokaryotes (Vandamme, E. J. , Ed. ), Weiheim: Wiley VCH, pp. 1-19. ISBN 978-3-527-30226-0

External links

• Polysaccharide Structure
• Applications and commercial sources of polysaccharides

homopolysaccharides : glucans