Polysaccharide starch

Polysaccharide (starch) Amylase Fragment polysaccharides into disaccharides (maltose) Salivary glands pancreas Mouth stomach small intestine... 

Carbohydrates (polysaccharides) — starches, cellulose of cotton and wood. 

A. Abbadi, K. F. Gotlieb, and H. van Bekkum, Study on solid acid catalyzed hydrolysis of maltose and related polysaccharides, Starch, 50 (1998) 23-28. 

Polysaccharides starch, glycogen and cellulose are polyacetals of glucose... 

Hydrogenation of the lateral chain of telomerized polysaccharides (starch, inulin) has been carried out using homogeneous RhCl(TPPTS)3 complex (0.8%) at40°C under 30 atm. H2 in H20/EtOH (5/1) mixture. Both terminal and substimted double bonds were successively hydrogenated [59]. 

Maltose is hydrolyzed by the enzyme maltase (specific for a-glycosidic linkage) to two units of glucose, but for the hydrolysis of cellobiose the enzyme emulsin (specific for (3-glycosidic linkage) is necessary. While maltose is the building block of the polysaccharide starch, cellobiose is the building block of another polysaccharide, cellulose. 

Amylase, which converts polysaccharides (starch or cellulose) to sugars. 

Starch occurs in potatoes, rice and wheat. Glucose, from which starch is polymerised, belongs to a group of simple carbohydrates known as monosaccharides. They are sweet to taste and soluble in water. Starch belongs to the more complicated group of carbohydrates known as polysaccharides. Starch does not form a true solution and it does not have a sweet taste. With iodine it gives an intense blue colour (nearly black), which is used as a test for starch or iodine itself (Figure 15.20). 

In more complicated molecules each end of these molecules can join up with further sugar units. When many hundreds of units of carbohydrates are linked together, the compounds are called polysaccharides . Starch and cellulose are such compounds. 

The large molecules of the polysaccharides (starches and cellulose) present in foods are too big for us to digest directly. Our bodies hydrolyse (i.e. action of water in the presence of an enzyme) the starches and break them up into smaller molecules, e.g. glucose. Our systems cannot hydrolyse the complicated long chains of sugar units in cellulose, but those of grazing animals can. 

P-Amylase Hydrolysis of a-l,4-glucan bonds in polysaccharides (starch, glycogen, etc.), yielding maltose and beta-limit dextrins. 

The term carbohydrate refers to a class of polyhydroxy aldehydes and polyhydroxy ketones with the general formula (CH O),. The name derives from the composition of the formula unit, that is, carbon plus water. All carbohydrates are composed of basic units called monosaccharides. Polymers containing two to six monosaccharides are called oligosaccharides those with more are called polysaccharides. Starch, cellulose, and glycogen are examples of polysaccharides. Monosaccharides and oligosaccharides are also called sugars. 

So far, our study of organic chemistry has dealt mainly with rather small molecules, containing perhaps as many as 50 to 75 atoms. But there also exist enormous molecules called macronwlecules, which contain hundreds of thousands of atoms. Some of these are naturally occurring, and make up classes of compounds that are, quite literally, vital the polysaccharides starch and cellulose, which provide us with food, clothing, and shelter (Chap. 35) proteins, which constitute much of the animal body, hold it together, and run it (Chap. 36) and nucleic acids, which control heredity on the molecular level (Chap. 37). 

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