Ribose-5-phosphate

Ribose-5-phosphate (or R5P) is a biochemical compound involved in the pentose phosphate pathway and the nucleotide synthesis. It is a monosaccharide (simple sugar) that consists of a five-carbon sugar, ribose, attached to a phosphate group.

Structure and Properties

Ribose-5-phosphate is a pentose sugar, meaning it has five carbon atoms. The "5-phosphate" refers to the phosphate group attached to the fifth carbon atom. This compound is a key intermediate in the pentose phosphate pathway, a metabolic pathway that generates NADPH and pentoses.

Biological Role

In the pentose phosphate pathway, ribose-5-phosphate is produced from glucose-6-phosphate by the sequential action of two enzymes: glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. The resulting ribose-5-phosphate can then be used in the synthesis of nucleotides, including adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP), and uridine triphosphate (UTP).

In addition to its role in nucleotide synthesis, ribose-5-phosphate is also a precursor for the synthesis of coenzyme A, flavin adenine dinucleotide (FAD), and nicotinamide adenine dinucleotide (NAD+).

Clinical Significance

Alterations in the metabolism of ribose-5-phosphate can lead to various health conditions. For example, a deficiency in glucose-6-phosphate dehydrogenase, the enzyme that initiates the pentose phosphate pathway, can lead to hemolytic anemia. This is because the lack of NADPH, a product of the pathway, makes red blood cells more susceptible to oxidative damage.

File:Ribose-5-phosphate.png

Chemical structure of ribose-5-phosphate

See Also

• Pentose phosphate pathway
• Nucleotide
• Glucose-6-phosphate dehydrogenase deficiency