Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl-pentose or a 6-deoxy-hexose. Rhamnose predominantly occurs in nature in its L-form as L-rhamnose (6-deoxy-L-mannose). This is unusual, since most of the naturally occurring sugars are in D-form. Exceptions are the methyl pentoses L-fucose and L-rhamnose and the pentose L-arabinose. However, examples of naturally-occurring D-rhamnose include some species of bacteria, such as Pseudomonas aeruginosa and Helicobacter pylori.[2]
Rhamnose is commonly bound to other sugars in nature. It is a common glycone component of glycosides from many plants. Rhamnose is also a component of the outer cell membrane of acid-fast bacteria in the Mycobacterium genus, which includes the organism that causes tuberculosis.[4] Natural antibodies against L-rhamnose are present in human serum,[5] and the majority of people seem to possess IgM, IgG or both of these types of immunoglobulins capable of binding this glycan.[6]
An interesting particularity of rhamnose is the presence of formaldehyde production when reacted with periodates in the vicinaldiol cleavage reaction, that makes it very useful to remove excess periodate in glycerol or other vicinal diol analysis, that would otherwise give colored blank issues.[7]
^Brown, M. R. (1991). "The amino-acid and sugar composition of 16 species of microalgae used in mariculture". Journal of Experimental Marine Biology and Ecology. 145: 79. doi:10.1016/0022-0981(91)90007-J.
^Golan, David E., ed. (2005). "Chapter 35 - Pharmacology of the Bacterial Cell Wall". Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy. Armen H. Tashjian Jr., Ehrin J. Armstrong, Joshua N. Galanter, April Wang Armstrong, Ramy A. Arnaout, Harris S. Rose. Lippincott Williams and Wilkins. p. 569. ISBN0-7817-4678-7.
^Wang X, Chen H, Chiodo F, Tefsen B (2019). "Detection of human IgM and IgG antibodies by means of galactofuranose-coated and rhamnose-coated gold nanoparticles". Matters. https://sciencematters.io/articles/201908000004
^Ashworth, M. R. F., ed. (1979). "Chapter 3". Analytical methods for glycerol. Academic Press.