Pentose

You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.

A pentose is a monosaccharide with five carbon atoms.

They either have an aldehyde functional group in position 1 (aldopentoses), or a ketone functional group in position 2 (ketopentoses).

The aldopentoses have three chiral centres ("asymmetric carbon atoms") and so 8 different stereoisomers are possible.

The 4 D-aldopentoses are:

 CH=O        CH=O          CH=O         CH=O
 |           |             |            |
HC-OH     HO-CH           HC-OH      HO-CH
 |           |             |            |
HC-OH       HC-OH       HO-CH        HO-CH
 |           |             |            |
HC-OH       HC-OH         HC-OH        HC-OH
 |           |             |            |
 CH2OH       CH2OH         CH2OH        CH2OH
D-Ribose    D-Arabinose   D-Xylose    D-Lyxose

A mnemonic suggested that can be used to remember the four D-aldopentoses is "ribs are extra lean."

The ketopentoses have 2 chiral centres and therefore 4 possible stereoisomers — ribulose (L- and D-form) and xylulose (L- and D-form).

The D-isomers of both are known to occur naturally as is the L-isomer of xylulose:

  CH2OH        CH2OH  
  |            |     
  C=O          C=O   
  |            |     
 HC-OH      HO-CH    
  |            |     
 HC-OH        HC-OH  
  |            |     
  CH2OH        CH2OH 
D-Ribulose    D-Xylulose  

The aldehyde and ketone functional groups in these carbohydrates react with neighbouring hydroxyl functional groups to form intramolecular hemiacetals or hemiketals, respectively. The resulting ring structure is related to furan, and is termed a furanose. The ring spontaneously opens and closes, allowing rotation to occur about the bond between the carbonyl group and the neighbouring carbon atom — yielding two distinct configurations (α and β). This process is termed mutarotation.

Ribose is a constituent of RNA, and the related deoxyribose of DNA.

See also

• Triose
• Tetrose
• Hexose
• Heptose

v • d • e Types of Carbohydrates
General:	Aldose | Ketose | Pyranose | Furanose
Geometry	Triose | Tetrose | Pentose | Hexose | Heptose | Cyclohexane conformation | Anomer | Mutarotation
Small/Large	Glyceraldehyde | Dihydroxyacetone | Erythrose | Threose | Erythrulose | Sedoheptulose
Trioses	Ketotriose (Dihydroxyacetone) | Aldotriose (Glyceraldehyde)
Tetroses	Erythrulose | Erythrose | Threose
Pentoses	Arabinose | Deoxyribose | Lyxose | Ribose | Ribulose | Xylose | Xylulose
Hexoses	Glucose | Galactose | Mannose | Gulose | Idose | Talose | Allose | Altrose | Fructose | Sorbose | Tagatose | Psicose | Fucose | Fuculose | Rhamnose
Disaccharides	Sucrose | Lactose | Trehalose | Maltose
Polymers	Glycogen | Starch (Amylose | Amylopectin) | Cellulose | Chitin | Stachyose | Inulin | Dextrin
Glycosaminoglycans	Heparin | Chondroitin sulfate | Hyaluronan | Heparan sulfate | Dermatan sulfate | Keratan sulfate
Aminoglycosides	Kanamycin | Streptomycin | Tobramycin | Neomycin | Paromomycin | Apramycin | Gentamicin | Netilmicin | Amikacin
Major families of biochemicals
Peptides | Amino acids | Nucleic acids | Carbohydrates | Nucleotide sugars | Lipids | Terpenes | Carotenoids | Tetrapyrroles | Enzyme cofactors | Steroids | Flavonoids | Alkaloids | Polyketides | Glycosides
Analogues of nucleic acids:		Analogues of nucleic acids:

ar:بنتوز

cs:Pentosa cy:Pentos da:Pentose de:Pentoseneo:Pentozo fr:Pentose id:Pentosa it:Pentosi mk:Пентоза nl:Pentose oc:Pentòsasr:Пентоза su:Péntosa fi:Pentoosi sv:Pentoser uk:Пентоза

Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .