Biochemistry-Ch 11. Carbohydrates
阮雪芬NTUT
Nov 4, 2002
Monosaccharides
The simplest carbohydrates (C-H2O)n
Carbon hydrate
enantiomers
Trioses
D-Aldoses Containing Three, Four, Five, and Six Carbon Atoms
D-Aldoses Containing Three, Four, Five, and Six Carbon Atoms
D-Aldoses Containing Three, Four, Five, and Six Carbon Atoms
D-Aldoses Containing Three, Four, Five, and Six Carbon Atoms
D-Aldoses Containing Three, Four, Five, and Six Carbon Atoms
D-Ketoses Containing Three, Four, Five, and Six Carbon Atoms
D-Ketoses Containing Three, Four, Five, and Six Carbon Atoms
D-Ketoses Containing Three, Four, Five, and Six Carbon Atoms
Pyranose Formation
Furanose Formation
Ring Structures of Fructose
: hydroxyl group attached to C-1 is below the plane of the ring.
: hydroxyl group attached to C-1 is above the plane of the ring.
Conformation of Pyranose and Furanose Rings
Pyranose and Furanose Rings are not planar.
Chair and Boat Forms of -D-glucopyranose
The chair form is more stable.
12
3
Envelop Conformations of -D-ribose
Four atoms are nearly coplanar and the fifth is about 0.5Å away from this plane.
4
5
1
23
4
5
O-glycosidic bond and N-glycosidic bond
NR2: N-glycosidic bond
Modified Monosaccharides
Modified Monosaccharides
Modified Monosaccharides
Modified Monosaccharides
Maltose, a disaccharide
Common Disaccharides (1)
glucose fructoseSucrase
Common Disaccharides (2)
Lactase: in human beings-galactosidase: in bacteria
galactose glucose
Common Disaccharides (3)
glucose glucoseMaltase
Electron Micrograph of a Microvillus
Polysaccharides
Large polymeric oligosaccharides Play vital roles in energy storage and in maintainin
g the structural integrity of an organism. If allof the monosaccharides are the same,these p
olymers are called homopolymers. In animal cells: Glycogen In plants: Starch
Amylose: the unbranched type Amylopectin: the branched type
Branch Point in Glycogen
Once in 10 units (glycogen)Once in 30 units (starch)
Starch and Glycogen
Starch:
Cellulose
One of the most abundant organic compounds in the biosphere.
The major structural polymer of plants Consists of linear chains of glucose units
Glycosaminoglycans
A different kind of repeating polysaccharide is present on the animal cell surface and in the extracellular matrix.
Many glycosaminoglycans are made of disaccharides repeating units containing a derivative of an amino sugar, either glucosamine or galactosamine
Repeating units in Glycosaminoglycans
Repeating units in Glycosaminoglycans
Repeating units in Glycosaminoglycans
Repeating units in Glycosaminoglycans
Repeating units in Glycosaminoglycans
