A heptose is a
monosaccharide with seven
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
atoms.
They have either an
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
functional group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...
in position 1 (aldoheptoses) or a
ketone functional group in position 2, 3 or 4 (ketoheptoses). Ketoheptoses have 4 chiral centers, whereas aldoheptoses have 5.
Examples
There are few examples of seven-carbon sugars in nature, among which are:
*
sedoheptulose or
D-''altro''-heptulose (a ketose), an intermediate in the Calvin cycle and in
lipid A biosynthesis
*
mannoheptulose (a ketose), found in
avocado
The avocado (''Persea americana'') is a medium-sized, evergreen tree in the laurel family ( Lauraceae). It is native to the Americas and was first domesticated by Mesoamerican tribes more than 5,000 years ago. Then as now it was prized for ...
es
*
L-''glycero''-
D-''manno''-heptose (an aldose), a late intermediate in lipid A biosynthesis.
References
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