Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl-

pentose In chemistry, a pentose is a monosaccharide (simple sugar) with five carbon atoms. The chemical formula of many pentoses is , and their molecular weight is 150.13 g/mol.hexose. Rhamnose predominantly occurs in nature in its L-form as L-rhamnose (6-deoxy-L-

mannose Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylat ...

). 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 Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. For biosynthetic reasons, most saccharides are almost always more abundant in nature as the "D"-form, or structural ...

. However, examples of naturally-occurring D-rhamnose include some species of bacteria, such as ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic– facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. a ...

'' and '' Helicobacter pylori''. Rhamnose can be isolated from

Buckthorn ''Rhamnus'' is a genus of about 110 accepted species of shrubs or small trees, commonly known as buckthorns, in the family Rhamnaceae. Its species range from tall (rarely to ) and are native mainly in east Asia and North America, but found thr ...

(''Rhamnus''), poison sumac, and plants in the genus '' Uncaria''. Rhamnose is also produced by

microalgae Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist indiv ...

belonging to class Bacillariophyceae (diatoms). Rhamnose is commonly bound to other sugars in nature. It is a common

glycone In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosi ...

component of

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

s from many plants. Rhamnose is also a component of the outer cell membrane of acid-fast bacteria in the ''

Mycobacterium ''Mycobacterium'' is a genus of over 190 species in the phylum Actinomycetota, assigned its own family, Mycobacteriaceae. This genus includes pathogens known to cause serious diseases in mammals, including tuberculosis ('' M. tuberculosis'') ...

'' genus, which includes the organism that causes

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, ...

. Natural antibodies against L-rhamnose are present in human serum, and the majority of people seem to possess IgM,

IgG Immunoglobulin G (Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG an ...

or both of these types of immunoglobulins capable of binding this glycan. An interesting particularity of rhamnose is the absence of

formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...

production when reacted with periodates in the vicinal diol cleavage reaction, that makes it very useful to remove excess periodate in

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

or other vicinal diol analysis, that would otherwise give colored blank issues.

See also

References

Further reading