Carbohydrates and Sugars
Carbohydrates and sugars
there are many simple sugars in nature
almost always optically active
glucose, galactose, glucuronic acid, xylose, arabinose, and fructose are primary metabolites and are the main sugars of plants
Calvin or reductive pentose phosphate pathway involves primary sugars as well.
sugars in combined forms with nucleotides
UDP-glucose common
2-deoxyhexoses, 6-deoxyhexoses, methoxy sugars, branched chain sugars, sugar acids, amino sugars (many in antibiotics) are all known. Most of these are secondary metabolites
Biological activity
sweet or bitter or no taste
sugar mimics - many of these have nitrogenous portions
many of the mimics can inhibit α and β-glucosidases and other sugar metabolizing enzymes
indolizidine alkaloids from Castanospermum and Swainsona (Fabaceae)
some pyrrolizidine alkaloids
some tropane type alkaloids
Sucrose
often involved in transport in phloem and in energy storage in some plants
Other disaccharides
Oligosaccharides
some breakdown of complex polysaccharides
some storage products
Storage carbohydrates
starch
algal polysaccharides
Structural carbohydrates
cellulose
callose
pectins
gums
Chitin
Biological activity of oligosaccharides and polysaccharides
food reserves
structure
kairomonal nitrogen fixing bacteria
cell recognition
Elicitors
Aphids
Sugar alcohols
polyols
cyclitols
L-Ascorbic acid
Related Images
Pyranose and furanose forms of sugars
Glucuronic acid and related sugar acids
© David S. Seigler, Integrative Biology 425, Plant Secondary Metabolism, Department of Plant
Biology, 265 Morrill Hall, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA.
217-333-7577. seigler@life.uiuc.edu.
