Category: Organic compounds

Nitrite, any member of either of two classes of compounds derived from nitrous acid. Salts of nitrous acid are ionic compounds containing the nitrite ion, NO–2, and a positive ion such as Na+ in sodium nitrite (NaNO2). Esters of nitrous acid are covalent compounds having the structure R―O―N―O, in which R represents a carbon-containing combining group such as ethyl (C2H5) in…

Angiotensin, a peptide, one form of which, angiotensin II, causes constriction of blood vessels. There are three forms of angiotensin. Angiotensin I is produced by the action of renin (an enzyme produced by the kidneys) on a protein called angiotensinogen, which is formed by the liver. Angiotensin I is transformed into angiotensin II in the blood by the action of angiotensin-converting enzyme (ACE). Angiotensin II acts directly on blood vessels, causing…

Lucite, trademark name of polymethyl methacrylate, a synthetic organic compound of high molecular weight made by combination of many simple molecules of the ester methyl methacrylate (monomer) into long chains (polymer); this process (polymerization) may be effected by light or heat, although chemical catalysts are usually employed in manufacture of the commercial product. The material has high dimensional stability and good resistance to…

Vitamin C, water-soluble, carbohydrate-like substance that is involved in certain metabolic processes of animals. Although most animals can synthesize vitamin C, it is necessary in the diet of some, including humans and other primates, in order to prevent scurvy, a disease characterized by soreness and stiffness of the joints and lower extremities, rigidity, swollen and bloody gums, and hemorrhages…

Maltase, enzyme that catalyzes the hydrolysis of the disaccharide maltose to the simple sugar glucose. The enzyme is found in plants, bacteria, and yeast; in humans and other vertebrates it is thought to be synthesized by cells of the mucous membrane lining the intestinal wall. During digestion, starch is partially transformed into maltose by the pancreatic or salivary enzymes called amylases; maltase secreted by the intestine then…

Theobromine, diuretic drug and major alkaloidal constituent of cocoa. Theobromine is a xanthine alkaloid, a methylxanthine, as are caffeine and theophylline, but it differs from them in having little stimulatory action upon the central nervous system. The stimulant effect of cocoa results from the caffeine that it contains rather than from the theobromine.

Nucleoside, a structural subunit of nucleic acids, the heredity-controlling components of all living cells, consisting of a molecule of sugar linked to a nitrogen-containing organic ring compound. In the most important nucleosides, the sugar is either ribose or deoxyribose, and the nitrogen-containing compound is either a pyrimidine (cytosine, thymine, or uracil) or a purine (adenine or guanine). Nucleosides are usually obtained by chemical or enzymatic decomposition…

Adenine, organic compound belonging to the purine family, occurring free in tea or combined in many substances of biological importance, including the nucleic acids, which govern hereditary characteristics of all cells. Partial decomposition of ribonucleic and deoxyribonucleic acids yields mixtures from which the compounds adenylic acid and deoxyadenylic acid, respectively, may be separated. These acids, called nucleotides, are phosphate esters of adenosine and deoxyadenosine, which…

A carbon atom (and therefore the molecule in which it occurs) becomes oxidized if it loses electron density during a reaction or becomes reduced if it gains electron density. A carbon atom loses electron density when it bonds to a more electronegative atom and gains electron density when it bonds to a less electronegative atom. The most…

For much of organic chemistry, an acid may be defined as a compound that can transfer a proton (H+) to a base, and a base may be defined as any entity with an unshared pair of electrons (and therefore capable of accepting a proton). In acid-base reactions a proton is transferred from an acid to a…