Heptose Explained

A heptose is a monosaccharide with seven carbon atoms.

They have either an aldehyde functional group 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^{[1] [2]}
• mannoheptulose (a ketose), found in avocadoes^[3]
• L-glycero-D-manno-heptose (an aldose), a late intermediate in lipid A biosynthesis.

Notes and References

1. 10.1021/ja01104a532. Transaldolase: The Formation of Fructose-6-Phosphate from Sedoheptulose-7-Phosphate. Journal of the American Chemical Society. 75. 8. 2021. 1953. Horecker. B. L. Smyrniotis. P. Z.
2. 10.1016/j.tibs.2014.06.005 . 25037503 . The pentose phosphate pathway and cancer . Trends in Biochemical Sciences . 39 . 8 . 347 . 2014 . Patra . Krushna C . Hay . Nissim . 4329227.
3. Liu . Xuan . Sievert . James . Arpaia . Mary Lu . Madore . Monica A. . Postulated Physiological Roles of the Seven-carbon Sugars, Mannoheptulose, and Perseitol in Avocado . Journal of the American Society for Horticultural Science . 2002-01-01 . 127 . 1 . 108–114 . 2018-06-26 . en . 10.21273/JASHS.127.1.108 . free .