por What is ribose?
Ribose is a five-carbon sugar found in ribonucleosides, ribonucleotides, and their derivatives. It may come by other names, such as β-D-ribofuranose, D-ribose, and L-ribose.
Nucleotides are the building blocks of the ribonucleic acid (RNA) backbone. Each nucleotide is made up of a base that can be adenine, guanine, cytosine, or uracil, a phosphate group, and a sugar, ribose.
This type of sugar is especially abundant in muscle tissue, where it is associated with ribonucleotides, particularly adenosine triphosphate, or ATP, essential for muscle function.
D-ribose was discovered in 1891 by Emil Fischer, and since then much attention has been paid to its physicochemical characteristics and its role in cellular metabolism, that is, as part of the ribonucleic acid backbone, ATP and various coenzymes.
Initially, this was obtained solely from the hydrolysis of yeast RNA, until, in the 1950s, it was synthesized from D-glucose in more or less accessible quantities, allowing the industrialization of its production.
Ribose Characteristics
Ribose is an aldopentose commonly extracted as a pure chemical compound in the form of D-ribose.
It is an organic substance soluble in water, white and crystalline in appearance. Being a carbohydrate, ribose possesses polar and hydrophilic characteristics.
It follows the common carbohydrate rule: it has the same number of carbon and oxygen atoms, and double that number of hydrogen atoms.
Through the carbon atoms at positions 3 or 5, this sugar can bind to a phosphate group, and if it binds to one of the RNA nitrogenous bases, a nucleotide is formed.
Ribose is most commonly found in nature as D-ribose and 2-deoxy-D-ribose, components of nucleotides and nucleic acids. D-ribose is a part of ribonucleic acid (RNA) and 2-deoxy-D-ribose of deoxyribonucleic acid (DNA).
In nucleotides, both types of pentose are found in the β-furanose (closed pentagonal ring) form.
In solution, free ribose is in equilibrium between the aldehyde (open-chain) form and the cyclic β-furanose form. However, the RNA contains only the cyclic form β-D-ribofuranose. The biologically active form is usually D-ribose.
ribose structure
Ribose is a sugar derived from glucose that belongs to the group of aldopentoses. Its molecular formula is C5H10O5 and it has a molecular weight of 150.13 g/mol. Since it is a monosaccharide sugar, its hydrolysis separates the molecule into its functional groups.
It has five carbon atoms that can be found cyclically as part of five-membered or six-membered rings. This sugar has an aldehyde group on carbon atom 1 and a hydroxyl group (-OH) on carbon atoms from position 2 to position 5 of the pentose ring.
The ribose molecule can be represented in the Fisher projection in two forms: D-ribose or L-ribose, with the L form being the stereoisomer and enantiomer of the D form and vice versa.
The classification of the D or L form depends on the orientation of the hydroxyl groups of the first carbon atom after the aldehyde group. If this group is oriented to the right side, the molecule representing Fisher corresponds to D-ribose, otherwise if it is to the left side (L-ribose).
The Haworth projection of ribose can be represented in two additional structures, depending on whether the orientation of the hydroxyl group on the carbon atom is anomeric. In the β position, the hydroxyl is oriented towards the top of the molecule, while the α position orients the hydroxyl towards the bottom.
Thus, according to the Haworth projection, there can be four possible forms: β-D-ribose, α-D-ribose, β-L-ribose or α-L-ribose.
When phosphate groups are attached to ribose, they are often called α, β, and Ƴ. Hydrolysis of nucleoside triphosphates provides the chemical energy to drive a wide variety of cellular reactions.
Ribose Functions
It has been proposed that ribose phosphate, a product of the breakdown of ribonucleotides, is one of the main precursors of furan and thiophenols, responsible for the characteristic odor of meat.
in cells
The chemical plasticity of ribose means that the molecule is involved in the vast majority of biochemical processes inside the cell, such as DNA translation, amino acid and nucleotide synthesis, etc.
Ribose constantly acts as a chemical vehicle inside the cell, since the nucleotides can have one, two or three phosphate groups covalently linked to each other by anhydrous bonds. These are known as mono-, di-, and triphosphate nucleosides, respectively.
The bond between ribose and phosphate is of the ester type, the hydrolysis of this bond releases approximately 14 kJ/mol under standard conditions, while that of each of the anhydride bonds releases approximately 30 kJ/mol.
In ribosomes, for example, the 2′-hydroxyl group of ribose can form a hydrogen bond with the various amino acids, a linkage that allows protein synthesis from tRNA in all known living organisms.
The venom of most snakes contains a phosphodiesterase that hydrolyzes nucleotides from the 3′ end that have a free hydroxyl, breaking the bonds between the 3′ hydroxyl of ribose or deoxyribose.
In medicine
In medicinal contexts it is used to improve performance and exercise capacity by increasing muscle energy. Chronic fatigue syndrome is also treated with this saccharide, as well as fibromyalgia and certain coronary artery diseases.
In preventive terms it is used to avoid muscle fatigue, cramps, pain and stiffness after exercise in patients with the hereditary disorder myoadenylate deaminase deficiency or AMP deaminase deficiency.
References
Alberts, B., Johnson, A., Lewis, J., Morgan, D., Raff, M., Roberts, K., & Walter, P. Molecular Biology of the Cell (6th ed.). New York: Garland Science.
Angyal, S. The Composition and Conformation of Sugars. Angewandte Chemie – International Edition.
Foloppe, N., & Mackerell, A.D. Conformational Properties of the Deoxyribose and Ribose Moieties of Nucleic Acids: A Quantum Mechanical Study.
Garrett, R., & Grisham, C. Biochemistry (4th ed.). Boston, USA: Brooks/Cole. CENGAGE Learning.
Guttman, B. Nucleotides and Nucleosides. Academic Press.