Nucleotides are organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common nutrients by the liver.
Uracil is one of the four nucleotide bases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine (T). Uracil is a demethylated form of thymine.
Nucleotide bases are nitrogen-containing biological compounds that form nucleosides, which, in turn, are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids. The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Five nucleobases—adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U)—are called primary or canonical. They function as the fundamental units of the genetic code, with the bases A, G, C, and T being found in DNA while A, G, C, and U are found in RNA. Thymine and uracil are distinguished by merely the presence or absence of a methyl group on the fifth carbon (C5) of these heterocyclic six-membered rings. In addition, some viruses have aminoadenine (Z) instead of adenine. It differs in having an extra amine group, creating a more stable bond to thymine.
Deoxyguanosine is composed of the purine nucleobase guanine linked by its N9 nitrogen to the C1 carbon of deoxyribose. It is similar to guanosine, but with one hydroxyl group removed from the 2' position of the ribose sugar. If a phosphate group is attached at the 5' position, it becomes deoxyguanosine monophosphate.
Thymidine, also known as deoxythymidine, deoxyribosylthymine, or thymine deoxyriboside, is a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine (A) in double-stranded DNA. In cell biology it is used to synchronize the cells in G1/early S phase. The prefix deoxy- is often left out since there are no precursors of thymine nucleotides involved in RNA synthesis.
In biochemistry, a ribonucleotide is a nucleotide containing ribose as its pentose component. It is considered a molecular precursor of nucleic acids. Nucleotides are the basic building blocks of DNA and RNA. Ribonucleotides themselves are basic monomeric building blocks for RNA. Deoxyribonucleotides, formed by reducing ribonucleotides with the enzyme ribonucleotide reductase (RNR), are essential building blocks for DNA. There are several differences between DNA deoxyribonucleotides and RNA ribonucleotides. Successive nucleotides are linked together via phosphodiester bonds.
A salvage pathway is a pathway in which a biological product is produced from intermediates in the degradative pathway of its own or a similar substance. The term often refers to nucleotide salvage in particular, in which nucleotides are synthesized from intermediates in their degradative pathway.
Floxuridine is an oncology drug that belongs to the class known as antimetabolites. Specifically, floxuridine is a pyrimidine analog, classified as a deoxyuridine. The drug is usually administered via an artery, and most often used in the treatment of colorectal cancer. The quality of life and survival rates of individuals that receive continuous hepatic artery infusion of floxuridine for colorectal cancer metastases is significantly higher than control groups. Floxuridine can also be prescribed for the treatment of kidney and stomach cancers. In vitro uses of floxuridine include 5-minute treatments of fluorouracil, floxuridine, and mitomycin to increase cell proliferation in Tenon's capsule fibroblasts.
Deoxyadenosine monophosphate (dAMP), also known as deoxyadenylic acid or deoxyadenylate in its conjugate acid and conjugate base forms, respectively, is a derivative of the common nucleotide AMP, or adenosine monophosphate, in which the -OH (hydroxyl) group on the 2' carbon on the nucleotide's pentose has been reduced to just a hydrogen atom. Deoxyadenosine monophosphate is abbreviated dAMP. It is a monomer used in DNA.
Oct-1-en-3-one (CH2=CHC(=O)(CH2)4CH3), also known as 1-octen-3-one or amyl vinyl ketone, is the odorant that is responsible for the typical "metallic" smell of metals and blood coming into contact with skin. Oct-1-en-3-one has a strong metallic mushroom-like odor with an odor detection threshold of 0.03–1.12 μg/m3 and it is the main compound responsible for the "smell of metal", followed by decanal (smell: orange skin, flowery) and nonanal (smell: tallowy, fruity). Oct-1-en-3-one is the degradative reduction product of the chemical reaction of skin lipid peroxides and Fe2+. Skin lipid peroxides are formed from skin lipid by oxidation, either enzymatically by lipoxygenases or by air oxygen. Oct-1-en-3-one is a ketone analog of the alkene 1-octene.
Normetanephrine, also called normetadrenaline, is a metabolite of norepinephrine created by action of catechol-O-methyl transferase on norepinephrine. It is excreted in the urine and found in certain tissues. It is a marker for catecholamine-secreting tumors such as pheochromocytoma.
Deoxyuridine monophosphate (dUMP), also known as deoxyuridylic acid or deoxyuridylate in its conjugate acid and conjugate base forms, respectively, is a deoxynucleotide.
3-Dehydrocarnitine is an aliphatic quaternary ammonium betaine that is part of the carnitine family. At physiological pH of 7.3, the major species of 3-dehydrocarnitine is its zwitterionic form, the conjugate base of 3-dehydrocarnitinium. 3-Dehydrocarnitine is classified as a short-chain keto acid, as it has a carbon chain containing less than six carbon atoms. It is an intermediate in carnitine degradation and is formed from D- or L-carnitine. The enzymes responsible for the degradation of carnitine to 3-dehydrocarnitine are carnitine-3-dehydrogenase or (S)-carnitine-3-dehydrogenase.
In Enzymology, a dUTP diphosphatase (EC 3.6.1.23) is an enzyme that catalyzes the chemical reaction
Glutaconyl-CoA is an intermediate in the metabolism of lysine. It is an organic compound containing a coenzyme substructure, which classifies it as a fatty ester lipid molecule. Being a lipid makes the molecule hydrophobic, which makes it insoluble in water. The molecule has a molecular formula of C26H40N7O19P3S, and a molecular weight 879.62 grams per mole.
2-Amino-3-carboxymuconic semialdehyde is an intermediate in the metabolism of tryptophan in the tryptophan-niacin catabolic pathway. Quinolinate is a neurotoxin formed nonenzymatically from 2-amino-3-carboxymuconic semialdehyde in mammalian tissues. 2-Amino-3-carboxymuconic semialdehyde is enzymatically converted to 2-aminomuconate via 2-aminomuconic semialdehyde.
3-Hydroxyisobutyric acid is an intermediate in the metabolism of valine. It is a chiral compound having two enantiomers, D-3-hydroxyisobutyric acid and L-3-hydroxyisobutyric acid.
Etiocholanolone glucuronide (ETIO-G) is an endogenous, naturally occurring metabolite of testosterone. It is formed in the liver from etiocholanolone by UDP-glucuronyltransferases. ETIO-G has much higher water solubility than etiocholanolone and is eventually excreted in the urine via the kidneys. Along with androsterone glucuronide, it is one of the major inactive metabolites of testosterone.
Etiocholanedione, also known as 5β-androstanedione or as etiocholane-3,17-dione, is a naturally occurring etiocholane (5β-androstane) steroid and an endogenous metabolite of androgens like testosterone, dihydrotestosterone, dehydroepiandrosterone (DHEA), and androstenedione. It is the C5 epimer of androstanedione (5α-androstanedione). Although devoid of androgenic activity like other 5β-reduced steroids, etiocholanedione has some biological activity of its own. The compound has been found to possess potent haematopoietic effects in a variety of models. In addition, it has been found to promote weight loss in animals and in a double-blind, placebo-controlled clinical study in humans conducted in 1993. These effects are said to be similar to those of DHEA. Unlike DHEA however, etiocholanedione cannot be metabolized further into steroid hormones like androgens and estrogens.
Fluorodeoxyuridylate, also known as FdUMP, 5-fluoro-2'-deoxyuridylate, and 5-fluoro-2'-deoxyuridine 5'-monophosphate, is a molecule formed in vivo from 5-fluorouracil and 5-fluorodeoxyuridine.
