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Agmatidine
Agmatidine (2-agmatinylcytidine, symbol C+ or agm2C) is a modified cytidine present in the wobble position of the anticodon of several archaeal AUA decoding tRNAs. Agmatidine is essential for correct decoding of the AUA codon in many archaea and is required for aminoacylation of tRNAIle2 with isoleucine. Introduction The genetic code describes how triplet codons on mRNA are translated into protein sequences by specific tRNA molecules which can base-pair with the codons. Precise decoding of the genetic code is a fundamental pre-requisite for long-term survival of all organisms. The nature of the anticodon decides the specificity of hydrogen bonding and hence the accuracy of decoding by tRNAs. Till date, a variety of post-transcriptional modifications have been discovered which aid tRNAs in increasing their repertoire of hydrogen bonding capacities. These modifications usually occur on the first base on the anticodon (position 34 or the wobble base position) which base pairs wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agmatine
Agmatine, also known as 4-aminobutyl-guanidine, is an aminoguanidine that was discovered in 1910 by Albrecht Kossel. Agmatine is a chemical substance which is naturally created from the amino acid arginine. Agmatine has been shown to exert modulatory action at multiple molecular targets, notably: neurotransmitter systems, ion channels, nitric oxide (NO) synthesis and polyamine metabolism and this provides bases for further research into potential applications. History Agmatine was discovered in 1910 by Albrecht Kossel. The term stems from A- (for amino-) + g- (from guanidine) + -ma- (from ptomaine) + -in (German)/-ine (English) suffix with insertion of -t- apparently for euphony. A year after its discovery, it was found that Agmatine could increase blood flow in rabbits; however, the physiological relevance of these findings were questioned given the high concentrations (high μM range) required. In the 1920s, researchers in the diabetes clinic of Oskar Minkowski have shown tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methionine
Methionine (symbol Met or M) () is an essential amino acid in humans. As the precursor of other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical role in the metabolism and health of many species, including humans. It is encoded by the codon AUG. Methionine is also an important part of angiogenesis, the growth of new blood vessels. Supplementation may benefit those suffering from copper poisoning. Overconsumption of methionine, the methyl group donor in DNA methylation, is related to cancer growth in a number of studies. Methionine was first isolated in 1921 by John Howard Mueller. Biochemical details Methionine (abbreviated as Met or M; encoded by the codon AUG) is an α-amino acid that is used in the biosynthesis of proteins. It contains a carboxyl group (which is in the deprotonated −COO− form under biological pH conditions), an amino group (which is in the protonated fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inosine
Inosine is a nucleoside that is formed when hypoxanthine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. It was discovered in 1965 in analysis of RNA transferase. Inosine is commonly found in tRNAs and is essential for proper translation of the genetic code in wobble base pairs. Knowledge of inosine metabolism has led to advances in immunotherapy in recent decades. Inosine monophosphate is oxidised by the enzyme inosine monophosphate dehydrogenase, yielding xanthosine monophosphate, a key precursor in purine metabolism. Mycophenolate mofetil is an anti-metabolite, anti-proliferative drug that acts as an inhibitor of inosine monophosphate dehydrogenase. It is used in the treatment of a variety of autoimmune diseases including granulomatosis with polyangiitis because the uptake of purine by actively dividing B cells can exceed 8 times that of normal body cells, and, therefore, this set of white cells (which cannot operate purine salvage p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleosides
Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar (ribose or 2'-deoxyribose) whereas a nucleotide is composed of a nucleobase, a five-carbon sugar, and one or more phosphate groups. In a nucleoside, the anomeric carbon is linked through a glycosidic bond to the N9 of a purine or the N1 of a pyrimidine. Nucleotides are the molecular building-blocks of DNA and RNA. List of nucleosides and corresponding nucleobases The reason for 2 symbols, shorter and longer, is that the shorter ones are better for contexts where explicit disambiguation is superfluous (because context disambiguates) and the longer ones are for contexts where explicit disambiguation is judged to be needed or wise. For example, when discussing long nucleobase sequences in genomes, the CATG symbol system is much preferable to the Cyt-Ade-Thy-Gua symbol system (see '' N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanosine
Guanosine (symbol G or Guo) is a purine nucleoside comprising guanine attached to a ribose (ribofuranose) ring via a β-N9-glycosidic bond. Guanosine can be phosphorylated to become guanosine monophosphate (GMP), cyclic guanosine monophosphate (cGMP), guanosine diphosphate (GDP), and guanosine triphosphate (GTP). These forms play important roles in various biochemical processes such as synthesis of nucleic acids and proteins, photosynthesis, muscle contraction, and intracellular signal transduction (cGMP). When guanine is attached by its N9 nitrogen to the C1 carbon of a deoxyribose ring it is known as deoxyguanosine. Physical and chemical properties Guanosine is a white, crystalline powder with no odor and mild saline taste. It is very soluble in acetic acid, slightly soluble in water, insoluble in ethanol, diethyl ether, benzene and chloroform. Functions Guanosine is required for an RNA splicing reaction in mRNA, when a "self-splicing" intron removes itself from the mRNA messag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine
Adenosine ( symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9-glycosidic bond. Adenosine is one of the four nucleoside building blocks of RNA (and its derivative deoxyadenosine is a building block of DNA), which are essential for all life. Its derivatives include the energy carriers adenosine mono-, di-, and triphosphate, also known as AMP/ADP/ATP. Cyclic adenosine monophosphate (cAMP) is pervasive in signal transduction. Adenosine is used as an intravenous medication for some cardiac arrhythmias. Adenosyl (abbreviated Ado or 5'-dAdo) is the chemical group formed by removal of the 5′-hydroxy (OH) group. It is found in adenosylcobalamin (an active form of vitamin B12) and as a radical in radical SAM enzymes. Medical uses Supraventricular tachycardia In individuals with supraventricular tachycardia (SVT), adenosine is used to help identify and convert the rhyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tautomer
Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydrogen atom within the compound. The phenomenon of tautomerization is called tautomerism, also called desmotropism. Tautomerism is for example relevant to the behavior of amino acids and nucleic acids, two of the fundamental building blocks of life. Care should be taken not to confuse tautomers with depictions of "contributing structures" in chemical resonance. Tautomers are distinct chemical species that can be distinguished by their differing atomic connectivities, molecular geometries, and physicochemical and spectroscopic properties, whereas resonance forms are merely alternative Lewis structure (valence bond theory) depictions of a single chemical species, whose true structure is best described as the "average" of the idealized, hypothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphodiester Bond
In chemistry, a phosphodiester bond occurs when exactly two of the hydroxyl groups () in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds. The "bond" involves this linkage . Discussion of phosphodiesters is dominated by their prevalence in DNA and RNA, but phosphodiesters occur in other biomolecules, e.g. acyl carrier proteins. Phosphodiester bonds make up the backbones of DNA and RNA. The phosphate is attached to the 5' carbon. The 3' carbon of one sugar is bonded to the 5' phosphate of the adjacent sugar. Specifically, the phosphodiester bond links the 3' carbon atom of one sugar molecule and the 5' carbon atom of another (hence the name, 3', 5' phosphodiester linkage). These saccharide groups are derived from deoxyribose in DNA and ribose in RNA. Phosphodiesters are negatively charged at pH 7. Repulsion between these negative charges influences the conformation of the polynucleic acids. The negative charge attracts histones, metal c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the -arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of proteins. It is encoded by the codons CGU, CGC, CGA, CGG, AGA, and AGG. The guanidine group in arginine is the precursor for the biosynthesis of nitric oxide. Like all amino acids, it is a white, water-soluble solid. History Arginine was first isolated in 1886 from yellow lupin seedlings by the German chemist Ernst Schulze and his assistant Ernst Steiger. He named it from the Greek ''árgyros'' (ἄργυρος) meaning "silver" due to the silver-white appearance of arginine nitrate crystals. In 1897, Schulze and Ernst Winterstein (1865–1949) determined the structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysidine (nucleoside)
Lysidine is an uncommon nucleoside, rarely seen outside of tRNA. It is a derivative of cytidine in which the carbonyl is replaced by the amino acid lysine. The third position in the anti-codon of the Isoleucine-specific tRNA, is typically changed from a cytidine which would pair with guanosine to a lysidine which will base pair with adenosine. Uridine could not be used at this position even though it is a conventional partner for adenosine since it will also "wobble base pair A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules. The four main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A), and hypox ..." with guanosine. So lysidine allows better translation fidelity. Lysidine is denoted as L or k2C (lysine bound to C2 atom of cytidine). : References {{reflist Nucleosides Pyrimidines Hydroxymethyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudouridine
Pseudouridine (abbreviated by the Greek letter psi- Ψ) is an isomer of the nucleoside uridine in which the uracil is attached via a carbon-carbon instead of a nitrogen-carbon glycosidic bond. (In this configuration, uracil is sometimes referred to as 'pseudouracil'.) Pseudouridine is the most abundant RNA modification in cellular RNA. After transcription and following synthesis, RNA can be modified with over 100 chemically distinct modifications. These can potentially regulate RNA expression post-transcriptionally, in addition to the four standard nucleotides and play a variety of roles in the cell including translation, localization and stabilization of RNA. Pseudouridine, being one of them, is the C5-glycoside isomer of uridine that contains a C-C bond between C1 of the ribose sugar and C5 of uracil, rather than usual C1-N1 bond found in uridine. The C-C bond gives it more rotational freedom and conformational flexibility. In addition, pseudouridine has an extra hydrogen bond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytidine
Cytidine (symbol C or Cyd) is a nucleoside molecule that is formed when cytosine is attached to a ribose ring (also known as a ribofuranose) via a β-N1- glycosidic bond. Cytidine is a component of RNA. It is a white water-soluble solid. which is only slightly soluble in ethanol. Dietary sources Dietary sources of cytidine include foods with high RNA (ribonucleic acid) content, such as organ meats, brewer's yeast, as well as pyrimidine-rich foods such as beer. During digestion, RNA-rich foods are broken-down into ribosyl pyrimidines (cytidine and uridine), which are absorbed intact. In humans, dietary cytidine is converted into uridine, which is probably the compound behind cytidine's metabolic effects. Cytidine analogues A variety of cytidine analogues are known, some with potentially useful pharmacology. For example, KP-1461 is an anti-HIV agent that works as a viral mutagen, and zebularine exists in '' E. coli'' and is being examined for chemotherapy. Low doses of azacit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
