The ribose is a five - carbon sugar that is present in ribonucleosides, ribonucleotides and its derivatives. It can be found under other names such as β-D-ribofuranose, D-ribose, and L-ribose.
Nucleotides are the constituent "building blocks" of the ribonucleic acid (RNA) backbone. Each nucleotide is composed of a base that can be adenine, guanine, cytosine or uracil, a phosphate group and a sugar, ribose.
Fisher's projection for D- and L-Ribose (Source: NEUROtiker via Wikimedia Commons)
This type of sugar is especially abundant in muscle tissues, where it is associated with ribonucleotides, particularly adenosine triphosphate or ATP, which is 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 skeleton of ribonucleic acid, ATP and various coenzymes.
At first, this was obtained only from the hydrolysis of yeast RNA, until, in the 1950s, it managed to be synthesized from D-glucose in more or less accessible quantities, allowing the industrialization of its production.
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, with a white and crystalline appearance. Being a carbohydrate, ribose has polar and hydrophilic characteristics.
Ribose meets the common carbohydrate rule: it has the same number of carbon and oxygen atoms, and twice this number in hydrogen atoms.
Through the carbon atoms in positions 3 or 5, this sugar can bind to a phosphate group, and if it binds to one of the nitrogenous bases of RNA, a nucleotide is formed.
The most common way to find ribose in nature is as D-ribose and 2-deoxy-D-ribose, these are components of nucleotides and nucleic acids. D-ribose is a part of ribonucleic acid (RNA) and 2-deoxy-D-ribose of deoxyribonucleic acid (DNA).
Structural differences between Ribose and Deoxyribose (Source: Genomics Education Program via Wikimedia Commons)
At nucleotides, both types of pentose are in the β-furanose form (closed pentagonal ring).
In solution, free ribose is in equilibrium between the aldehyde (open chain) form and the cyclic β-furanose form. However, RNA contains only the cyclic form β-D-ribofuranose. The biologically active form is usually D-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, as its formula indicates, five carbon atoms that can be found cyclically as part of five- or six-membered rings. This sugar has an aldehyde group at carbon 1 and a hydroxyl group (-OH) at carbon atoms from position 2 to position 5 of the pentose ring.
The ribose molecule can be represented in the Fisher projection in two ways: D-ribose or L-ribose, the L-form being the stereoisomer and the 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 towards the right side, the molecule representing Fisher corresponds to D-ribose, otherwise if it is towards the left side (L-ribose).
The Haworth projection of ribose can be represented in two additional structures depending on the orientation of the hydroxyl group on the carbon atom that is anomeric. In the β position the hydroxyl is oriented towards the upper part of the molecule, while the α position orients the hydroxyl towards the bottom.
Haworth projection for Ribopyranose and Ribofuranose (Source: NEUROtiker via Wikimedia Commons)
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 referred to as α, β, and Ƴ. The hydrolysis of nucleoside triphosphate provides the chemical energy to drive a wide variety of cellular reactions.
Features
It has been proposed that ribose phosphate, product of the decomposition of ribonucleotides, is one of the main precursors of furan and thiophenols, which are responsible for the characteristic odor of meat.
In cells
The chemical plasticity of ribose makes the molecule involved in the vast majority of biochemical processes inside the cell, some such as the translation of DNA, synthesis of amino acids and nucleotides, etc.
Ribose constantly acts as a chemical vehicle inside the cell, since nucleotides can have one, two or three phosphate groups covalently linked to each other by anhydrous bonds. These are known as nucleosides mono-, di- and triphosphate, 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 various amino acids, a bond that allows protein synthesis from tRNAs 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 diseases of the coronary artery.
In preventive terms, it is used to prevent muscle fatigue, cramps, pain and stiffness after exercise in patients with the inherited disorder of myoadenylate deaminase deficiency or AMP deaminase deficiency.
References
- Alberts, B., Johnson, A., Lewis, J., Morgan, D., Raff, M., Roberts, K., & Walter, P. (2015). Molecular Biology of the Cell (6th ed.). New York: Garland Science.
- Angyal, S. (1969). The Composition and Conformation of Sugars. Angewandte Chemie - International Edition, 8 (3), 157–166.
- Foloppe, N., & Mackerell, AD (1998). Conformational Properties of the Deoxyribose and Ribose Moieties of Nucleic Acids: A Quantum Mechanical Study, 5647 (98), 6669–6678.
- Garrett, R., & Grisham, C. (2010). Biochemistry (4th ed.). Boston, USA: Brooks / Cole. CENGAGE Learning.
- Guttman, B. (2001). Nucleotides and Nucleosides. Academic Press, 1360–1361.
- Mathews, C., van Holde, K., & Ahern, K. (2000). Biochemistry (3rd ed.). San Francisco, California: Pearson.
- Mottram, DS (1998). Flavor formation in meat and meat products: a review. Food Chemistry, 62 (4), 415-424.
- Nechamkin, H. (1958). Some interesting etymological derivations of chemical terminology. Chemical Terminology, 1–12.
- Nelson, DL, & Cox, MM (2009). Lehninger Principles of Biochemistry. Omega Editions (5th ed.).
- Shapiro, R. (1988). Prebiotic Ribose Synthesis: A Critical Analysis. Origins of Life and Evolution of the Biosphere, 18, 71–85.
- The Merck Index Online. (2018). Retrieved from www.rsc.org/Merck-Index/monograph/m9598/dribose?q=unauthorize
- Waris, S., Pischetsrieder, M., & Saleemuddin, M. (2010). DNA damage by ribose: Inhibition at high ribose concentrations. Indian Journal of Biochemistry & Biophysics, 47, 148-156.
- WebMD. (2018). Retrieved April 11, 2019, from www.webmd.com/vitamins/ai/ingredientmono-827/ribose
- Wulf, P., & Vandamme, E. (1997). Microbial Synthesis of D-Ribose: Metabolic Deregulation and Fermentation Process. Advances in Applied Microbiology, 4, 167–214.
- Xu, Z., Sha, Y., Liu, C., Li, S., Liang, J., Zhou, J., & Xu, H. (2016). L -Ribose isomerase and mannose-6-phosphate isomerase: properties and applications for L -ribose production. Applied Microbiology and Biotechnology, 1–9.