Ribulose is a

ketopentose 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.monosaccharide Monosaccharides (from Greek '' monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. Chemically, monosaccharides are polyhy ...

containing five

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

s, and including a

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...

. It has

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

. Two

enantiomers In chemistry, an enantiomer (Help:IPA/English, /ɪˈnænti.əmər, ɛ-, -oʊ-/ Help:Pronunciation respelling key, ''ih-NAN-tee-ə-mər''), also known as an optical isomer, antipode, or optical antipode, is one of a pair of molecular entities whi ...

are possible, -ribulose (-erythro-pentulose) and -ribulose (-erythro-pentulose). -Ribulose is the

diastereomer In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have di ...

of -

xylulose Xylulose is a ketopentose, a monosaccharide containing five carbon atoms, and including a ketone functional group. It has the chemical formula . In nature, it occurs in both the L- and D-enantiomers. 1-Deoxyxylulose is a precursor to terpenes via ...

. Ribulose sugars are composed in the

pentose phosphate pathway The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt or HMP shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (five-carbon sugars) as well as ribose 5-ph ...

from

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

. They are important in the formation of many bioactive substances. For example, -ribulose is an intermediate in the fungal pathway for -

arabitol Arabitol, or arabinitol, is a sugar alcohol. It can be formed by the reduction of either arabinose or lyxose. Some organic acid tests check for the presence of D-arabitol, which may indicate overgrowth of intestinal microbes such as '' Candida ...

production. Also, as the 1,5-bisphosphate, -ribulose combines with

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

at the start of the

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

process in green plants (carbon dioxide trap). Ribulose has the same stereochemistry at carbons 3 and 4 as the five-carbon

aldose An aldose is a monosaccharide (a simple sugar) with a carbon backbone chain with a carbonyl group on the endmost carbon atom, making it an aldehyde, and hydroxyl groups connected to all the other carbon atoms. Aldoses can be distinguished from ket ...

ribose Ribose is a simple sugar and carbohydrate with molecular formula C5H10O5 and the linear-form composition H−(C=O)−(CHOH)4−H. The naturally occurring form, , is a component of the ribonucleotides from which RNA is built, and so this comp ...

and

References

{{Carbohydrates Ketopentoses