Fructan

Fructans (also fructosans, Fruktosane, polyfructosans, polyfructoses ) is the name of a group of water-soluble oligo-and polysaccharides, which replace in some plant taxa starch as a storage carbohydrate or supplement. Fructans are composed almost entirely of D- fructose units.

Structure

Fructans are characterized in that one or several (many ) fructose molecules are bound to one molecule of sucrose.

Depending on the binding site of the fructosyl sucrose at the one distinguishes three fructan basic types:

Pure homologous series of a logic operation, however, are rare. Especially with grasses occur frequently all three link styles mixed up, so there are very complex branching pattern.

Occurrence

Fructans come with some groups before the bacteria and levans are mentioned here. Levan is characterized by a high degree of polymerization of (over 100) and has β -2 ,6- bonds. The biosynthesis of levans differs substantially from that in higher plants.

Fructans occur sporadically in some green algae on ( Dasycladales, Cladophorales ) and mosses ( Sphagnales, Jungermanniales ). In ferns and gymnosperms not yet fructans were detected.

Among the monocotyledons ( monocots ), the lily -like and asparagus -like fructans have to Neokestosebasis that Süßgrasartigen ( Poales ) most diverse and sometimes very complex Fruktanmuster. In the dicotyledons ( dicots ) can be found at the Aster -like fructans, Raublattgewächsen ( Boraginaceae ) and carding -like ( Dipsacales ). Here it is expected to always act to fructans of the inulin type.

Importance

Some plants accumulate fructans in drought. Thus, the drought are tolerated better. On the one hand because the higher solute concentration in the osmotic potential of the plant cell is increased and water can thereby be more easily absorbed by the plant. On the other hand, to protect the cell membranes fructans.

Since humans only α -1, 6 and α -1, 4 linked can digest oligo -and polysaccharides, fructans is suitable as a sweetener for diabetics.

In strong sunlight, while low temperatures obtained by sunlight energy grasses can not be directly translated into growth and is therefore cached in the form of fructans. This is mainly due to the first sunny spring days and in late autumn the case. The resulting concentration of multiple sugars can lead to laminitis in horses.