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Cyanogenic Glycosides
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of ''Heliconius'' butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body. In formal terms, a glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond. Glycosides can be linked by an O- (an ''O-glycoside''), N- (a ''glycosylamine''), S-(a ''thioglycoside''), or C- (a '' C-glycoside'') glycosidic bond. According to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Misnomer
A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the name no longer suitably applies. A misnomer may also be simply a word that someone uses incorrectly or misleadingly. The word "misnomer" does not mean " misunderstanding" or " popular misconception", and a number of misnomers remain in common usage — which is to say that a word being a misnomer does not necessarily make usage of the word incorrect. Sources of misnomers Some of the sources of misnomers are: * An older name being retained after the thing named has changed (e.g., tin can, mince meat pie, steamroller, tin foil, clothes iron, digital darkroom). This is essentially a metaphorical extension with the older item standing for anything filling its role. * Transference of a well-known product brand name into a genericized tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoproteins
Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated. In proteins that have segments extending extracellularly, the extracellular segments are also often glycosylated. Glycoproteins are also often important integral membrane proteins, where they play a role in cell–cell interactions. It is important to distinguish endoplasmic reticulum-based glycosylation of the secretory system from reversible cytosolic-nuclear glycosylation. Glycoproteins of the cytosol and nucleus can be modified through the reversible addition of a single GlcNAc residue that is considered reciprocal to phosphorylation and the functions of these are likely to be an additional regulatory mechanism that controls phosphorylation-based signalling. In contrast, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoconjugates
Glycoconjugates are the classification family for carbohydrates – referred to as glycans – which are covalently linked with chemical species such as proteins, peptides, lipids, and other compounds. Glycoconjugates are formed in processes termed glycosylation. Glycoconjugates are very important compounds in biology and consist of many different categories such as glycoproteins, glycopeptides, peptidoglycans, glycolipids, glycosides, and lipopolysaccharides. They are involved in cell–cell interactions, including cell–cell recognition; in cell–matrix interactions; in detoxification processes. Generally, the carbohydrate part(s) play an integral role in the function of a glycoconjugate; prominent examples of this are neural cell adhesion molecule (NCAM) and blood proteins where fine details in the carbohydrate structure determine cell binding (or not) or lifetime in circulation. Although the important molecular species DNA, RNA, ATP, cAMP, cGMP, NADH, NADPH, and coenzy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Union Of Pure And Applied Chemistry
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is a member of the International Science Council (ISC). IUPAC is registered in Zürich, Switzerland, and the administrative office, known as the "IUPAC Secretariat", is in Research Triangle Park, North Carolina, United States. This administrative office is headed by IUPAC's executive director, currently Lynn Soby. IUPAC was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry. Its members, the National Adhering Organizations, can be national chemistry societies, national academies of sciences, or other bodies representing chemists. There are fifty-four National Adhering Organizations and three Associate National Adhering Organizations. IUPAC's Inter-divisional Committee on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells,Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function.Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre-Jean Robiquet
Pierre Jean Robiquet (13 January 1780 – 29 April 1840) was a French chemist. He laid founding work in identifying amino acids, the fundamental building blocks of proteins. He did this through recognizing the first of them, asparagine, in 1806, in the industry's adoption of industrial dyes, with the identification of alizarin in 1826, and in the emergence of modern medications, through the identification of codeine in 1832, a opiate alkaloid substance of widespread use with analgesic and antidiarrheal properties. Robiquet was born in Rennes. He was at first a pharmacist in the French armies during the French Revolution years and became a professor at the École de pharmacie in Paris, where he died. Notable scientific achievements were among other things his isolation and characterization of properties of asparagine (the first amino acid to be identified, from asparagus, achieved. In 1806, with Louis Nicolas Vauquelin), cantharidin (1810), the sigma-1 receptor agonist noscapin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amygdalin
Amygdalin (from Ancient Greek: ' "almond") is a naturally occurring chemical compound found in many plants, most notably in the seeds (kernels) of apricots, bitter almonds, apples, peaches, cherries, and plums. Amygdalin is classified as a cyanogenic glycoside because each amygdalin molecule includes a nitrile group, which can be released as the toxic cyanide anion by the action of a beta-glucosidase. Eating amygdalin will cause it to release cyanide in the human body, and may lead to cyanide poisoning. Since the early 1950s, both amygdalin and a chemical derivative named ''laetrile'' have been promoted as alternative cancer treatments, often under the misnomer vitamin B17 (neither amygdalin nor laetrile is a vitamin). Scientific study has found them to not only be clinically ineffective in treating cancer, but also potentially toxic or lethal when taken by mouth due to cyanide poisoning. The promotion of laetrile to treat cancer has been described in the medical literature a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligosaccharide
An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sugars). Oligosaccharides can have many functions including cell recognition and cell adhesion. They are normally present as glycans: oligosaccharide chains are linked to lipids or to compatible amino acid side chains in proteins, by ''N''- or ''O''-glycosidic bonds. ''N''-Linked oligosaccharides are always pentasaccharides attached to asparagine via a beta linkage to the amine nitrogen of the side chain.. Alternately, ''O''-linked oligosaccharides are generally attached to threonine or serine on the alcohol group of the side chain. Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrins or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disaccharide
A disaccharide (also called a double sugar or ''biose'') is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, lactose, and maltose. Disaccharides are one of the four chemical groupings of carbohydrates (monosaccharides, disaccharides, oligosaccharides, and polysaccharides). The most common types of disaccharides—sucrose, lactose, and maltose—have 12 carbon atoms, with the general formula C12H22O11. The differences in these disaccharides are due to atomic arrangements within the molecule. The joining of monosaccharides into a double sugar happens by a condensation reaction, which involves the elimination of a water molecule from the functional groups only. Breaking apart a double sugar into its two monosaccharides is accomplished by hydrolysis with the help of a type of enzyme called a disaccharidase. As building the larger sugar ejects a water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monosaccharide
Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-soluble, and crystalline solids. Contrary to their name (sugars), only some monosaccharides have a sweet taste. Most monosaccharides have the formula (though not all molecules with this formula are monosaccharides). Examples of monosaccharides include glucose (dextrose), fructose (levulose), and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch). The table sugar used in everyday vernacular is itself a disaccharide sucrose comprising one molecule of each of the two monosaccharides D-glucose and D-fructose. Each carbon atom that supports a hydroxyl group is chiral, except those at the end of the chain. This gives rise to a number of isomeric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aglycone
An aglycone (aglycon or genin) is the compound remaining after the glycosyl group on a glycoside is replaced by a hydrogen atom. For example, the aglycone of a cardiac glycoside would be a steroid molecule. Detection A way to identify aglycone is proposed to extract it from Agave spp. by using H-NMR and Heteronuclear multiple bond correlation (HMBC) experiments. The HMBC experiment can be combined with other techniques such as mass spectrometry to further examine the structure and the function of aglycone. Samples of glycones and glycosides from limonoids can be simultaneously quantified through a high performance liquid chromatography (HPLC) method, where a binary solvent system and a diode array detector separate and detect them at a sensitivity of 0.25-0.50 µg. Clinical significance A study on molecular markers in human aortic endothelial cells published that aglycone stopped cell migration but not monocyte adhesion, which is the initial step of atherosclerotic plaq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
