Monosaccharides


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Monosaccharides

 

organic compounds; one of the major groups of carbohydrates. They contain hydroxyl and aldehyde groups (aldoses) or keto groups (ketoses). Monosaccharides are divided into trioses, tetroses, pentoses, hexoses, and so on (containing three, four, five, six, or more carbon atoms in the chain). Natural monosaccharides with a carbon chain containing more than nine carbon atoms have not been found.

For monosaccharides containing n asymmetric carbon atoms, 2n stereoisomers may exist. Monosaccharides enter into chemical reactions typical of carbonyl and hydroxyl groups.

A characteristic feature of monosaccharides is their ability to exist in open (acyclic) or cyclic forms and to produce derivatives of each form. Monosaccharides containing a five-member ring are called furanoses, and those containing a six-member ring are called pyranoses.

Monosaccharides are components of complex carbohydrates (glycosides, oligosaccharides, and polysaccharides) and mixed carbohydrate-containing biopolymers (glycoproteins and glycolipids). In such compounds, monosaccharides are bound to one another and to the noncarbohydrate portion of the molecule by glycoside bonds. Upon acid or enzyme hydrolysis, the bonds may cleave, with the release of the monosaccharides.

Free monosaccharides, with the exception of D-glucose and D-fructose, are rarely encountered in nature. The biosynthesis of monosaccharides from carbon dioxide and water takes place in plants during photosynthesis. As a rule, biosynthesis of complex carbohydrates takes place with the participation of activated monosaccharide derivatives, nucleoside diphosphate sugars.

The decomposition of monosaccharides in the organism (for example, alcoholic fermentation; glycolysis) is accompanied by the release of energy. Some free monosaccharides and their derivatives (for example, glucose, fructose, and fructose diphosphate) are used in the food industry and in medicine.

REFERENCE

Khimiia uglevodov. Moscow, 1967.

L. V. BAKINOVSKII

References in periodicals archive ?
The release of monosaccharides caused by exogenous enzymes is due to two reasons: firstly, the breakdown of NSP led to release of their respective monosaccharides, and secondly, the breakdown of NSP released the starch within the endosperm, which was exposed to the endogenous amylase, releasing more glucose (Malathi and Devegowda, 2001).
The WHO's limits on intake of sugars apply to all monosaccharides (such as glucose, fructose) and disaccharides (such as sucrose or table sugar).
From there, more and more monosaccharides jump on, forming a conga line of sugars.
Honey has high levels of monosaccharides, fructose and glucose, containing about 70 to 80% sugar, which gives it its sweet taste - minerals and water make up the rest of its composition.
FODMAP" is a rather clunky acronym for a certain kind of fermentable, short-chain carbohydrate: specifically, the word stands for fermentable, oligo-, di-, monosaccharides, and polyols.
The polysaccharide concentration and protein contents were determined, and the monosaccharides and amino acids compositions were analyzed as described by Kim et al.
Comparatively, Switchgrass biomass contained 2-5% more of major fermentable monosaccharides than the closest woody species, Autumn Olive.
12) Meanwhile, research had been taking place into a group of short chain carbohydrates poorly absorbed in the small intestine, commonly known as FODMaPs--an acronym for fermentable oligosaccharides, disaccharides, monosaccharides and polyols.
The authors speculate that the reason for the greater protective effect of vegetables over fruit may include a higher vitamin E content of vegetables although other compositional differences such as dietary fibres, lycopenes, [beta]-carotenoids and monosaccharides cannot be ruled out.
Kaden Biochemicals' rare sugar lines include monosaccharides, disaccharides and trisaccharides such as rhamnose, arabinose, and galactose.
This fruit contain antioxidants, complex polysaccharides (proteoglycan, which are considered to be the source of its beneficial effects on health) and monosaccharides, lutein and zeaxanthin (beneficial for the eyes), fiber, proteins and carbohydrates.