Ketopentose

A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups: Aldopentoses have an aldehyde functional group at position 1. Ketopentoses have a ketone functional group at position 2 or 3. In the cell, pentoses have a higher metabolic stability than hexoses. A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups: Aldopentoses have an aldehyde functional group at position 1. Ketopentoses have a ketone functional group at position 2 or 3. In the cell, pentoses have a higher metabolic stability than hexoses. The aldopentoses have three chiral centers; therefore, eight (23) different stereoisomers are possible. Ribose is a constituent of RNA, and the related molecule, deoxyribose, is a constituent of DNA. Phosphorylated pentoses are important products of the pentose phosphate pathway, most importantly ribose 5-phosphate (R5P), which is used in the synthesis of nucleotides and nucleic acids, and erythrose 4-phosphate (E4P), which is used in the synthesis of aromatic amino acids. The 2-ketopentoses have two chiral centers; therefore, four (22) different stereoisomers are possible. The 3-ketopentoses are rare.