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Syn-propanethial-S-oxide
''syn''-Propanethial ''S''-oxide (or (''Z'')-propanethial ''S''-oxide), a member of a class of organosulfur compounds known as thiocarbonyl ''S''-oxides (formerly "sulfines"), is a volatile liquid that acts as a lachrymatory agent (triggers tearing and stinging on contact with the eyes). The chemical is released from onions, ''Allium cepa'', as they are sliced. The release is due to the breaking open of the onion cells and their releasing enzymes called alliinases, which then break down amino acid sulfoxides, generating sulfenic acids. A specific sulfenic acid, 1-propenesulfenic acid, formed when onions are cut, is rapidly rearranged by a second enzyme, called the lachrymatory factor synthase or LFS, giving ''syn''-propanethial ''S''-oxide. The gas diffuses through the air and, on contact with the eye, it stimulates sensory neurons creating a stinging, painful sensation. Tears are released from the tear glands to dilute and flush out the irritant. A structurally related lachryma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organosulfur
Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur is vital for life. Of the 20 common amino acids, two (cysteine and methionine) are organosulfur compounds, and the antibiotics penicillin and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries. Sulfur shares the chalcogen group with oxygen, selenium, and tellurium, and it is expected that organosulfur compounds have similarities with carbon–oxygen, carbon–selenium, and carbon–tellurium compounds. A classical chemical test for the detection of sulfur compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alliinase
In enzymology, an alliin lyase () is an enzyme that catalyzes the chemical reaction :an ''S''-alkyl-L-cysteine ''S''-oxide \rightleftharpoons an alkyl sulfenate + 2-aminoacrylate Hence, this enzyme has one substrate, ''S''-alkyl-L-cysteine ''S''-oxide, and two products, alkyl sulfenate and 2-aminoacrylate. This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is ''S''-alkyl-L-cysteine ''S''-oxide alkyl-sulfenate-lyase (2-aminoacrylate-forming). Other names in common use include alliinase, cysteine sulfoxide lyase, alkylcysteine sulfoxide lyase, ''S''-alkylcysteine sulfoxide lyase, L-cysteine sulfoxide lyase, ''S''-alkyl-L-cysteine sulfoxide lyase, and alliin alkyl-sulfenate-lyase. It employs one cofactor, pyridoxal phosphate. Many alliinases contain a novel ''N''-terminal epidermal growth factor-like domain ( EGF-like domain). Occurrence These enzymes are found in plants of the genus ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organosulfur Compounds
Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur is vital for life. Of the 20 common amino acids, two ( cysteine and methionine) are organosulfur compounds, and the antibiotics penicillin and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries. Sulfur shares the chalcogen group with oxygen, selenium, and tellurium, and it is expected that organosulfur compounds have similarities with carbon–oxygen, carbon–selenium, and carbon–tellurium compounds. A classical chemical test for the detection of sulfur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allium Siculum
''Allium siculum'' ( syn. ''Nectaroscordum siculum''), known as honey garlic, Sicilian honey lily, Sicilian honey garlic, or Mediterranean bells, is a European and Turkish species of plants genus ''Allium''. It is native to the regions around the Mediterranean and Black Seas, and grown in other regions as an ornamental and as a culinary herb. Description It has showy clusters of gracefully drooping bell-shaped blossoms produced in May to early June sitting atop a tall green stem, to 1.2 m in height. The florets (blossoms), suspended on long drooping pedicels, are cream colored with a maroon streak down each petal, have white flared tips, and are tinted green at the base. The blossoms are followed by decorative, erect seed pods in late summer. The blue-gray foliage is triangular in cross-section and strongly twisting along the length of the ascending leaves. A penetrating, skunky odor is released when the plant is cut. Distribution and habitat ''Allium siculum'' is native to Tur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfenic Acid
In chemistry, a sulfenic acid is an organosulfur compound and oxoacid with the general formula . It is the first member of the family of organosulfur oxoacids, which also include sulfinic acids () and sulfonic acids (), respectively. The base member of the sulfenic acid series with R = H is hydrogen thioperoxide. Properties In contrast to sulfinic and sulfonic acids, simple sulfenic acids, such as methanesulfenic acid, CH3SOH, are highly reactive and cannot be isolated in solution. In the gas phase the lifetime of methanesulfenic acid is about one minute. The gas phase structure of methanesulfenic acid was found by microwave spectroscopy (rotational spectroscopy) to be CH3–S–O–H. Sulfenic acids can be stabilized through steric effects, which prevent the sulfenic acid from condensing with itself to form thiosulfinates, RS(O)SR, such as allicin from garlic. Through the use of X-ray crystallography, the structure of such stabilized sulfenic acids were shown to be R–S–O–H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onions
An onion (''Allium cepa'' L., from Latin ''cepa'' meaning "onion"), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the onion which was classified as a separate species until 2010. Its close relatives include garlic, scallion, leek, and chive. This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (''Allium fistulosum''), the tree onion (''A.'' × ''proliferum''), and the Canada onion (''Allium canadense''). The name '' wild onion'' is applied to a number of ''Allium'' species, but ''A. cepa'' is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions. The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onions
An onion (''Allium cepa'' L., from Latin ''cepa'' meaning "onion"), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the onion which was classified as a separate species until 2010. Its close relatives include garlic, scallion, leek, and chive. This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (''Allium fistulosum''), the tree onion (''A.'' × ''proliferum''), and the Canada onion (''Allium canadense''). The name '' wild onion'' is applied to a number of ''Allium'' species, but ''A. cepa'' is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions. The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfine
Sulfinylmethane or sulfine is an organic compound with molecular formula H2CSO. It is the simplest sulfine. Sulfines are chemical compounds with the general structure XY=SO. IUPAC considers the term 'sulfine' obsolete, preferring instead thiocarbonyl ''S''-oxide, despite this the use of the term sulfine still predominates in the chemical literature. Substituted sulfines The parent sulfine H2CSO is very labile, whereas substituted derivatives are more conveniently isolated. One example is syn-propanethial-S-oxide which is produced from allicin and is responsible for eye-watering effects of cutting onions. Another example is diphenylsulfine, obtained by oxidation of thiobenzophenone: :(C6H5)2C=S + → (C6H5)2C=S=O See also * Sulfene - related functional group with the formula H2C=SO2 *Ethenone *Heterocumulene A heterocumulene is a molecule or ion containing a chain of at least three double bonds between consecutive atoms, in which one or more atoms in the doubly bonded ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzymes
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiocarbonyl
In organic chemistry, thioketones (; also known as thiones or thiocarbonyls) are organosulfur compounds related to conventional ketones in which the oxygen has been replaced by a sulfur. Instead of a structure of , thioketones have the structure , which is reflected by the prefix "thio-" in the name of the functional group. Unhindered alkylthioketones typically tend to form polymers or rings. Structure and bonding The C=S bond length of thiobenzophenone is 1.63 Å, which is comparable to 1.64 Å, the C=S bond length of thioformaldehyde, measured in the gas phase. Due to steric interactions, the phenyl groups are not coplanar and the dihedral angle SC-CC is 36°. Unhindered dialkylthiones polymerize or oligomerize but thiocamphor is well characterized red solid. Consistent with the double bond rule, most alkyl thioketones are unstable with respect to dimerization.Organosulfur Chemistry I: Topics in Current Chemistry, 1999, Volume 204/1999, 127-181, The energy difference bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it is the oldest continuously published magazine in the United States. ''Scientific American'' is owned by Springer Nature, which in turn is a subsidiary of Holtzbrinck Publishing Group. History ''Scientific American'' was founded by inventor and publisher Rufus Porter in 1845 as a four-page weekly newspaper. The first issue of the large format newspaper was released August 28, 1845. Throughout its early years, much emphasis was placed on reports of what was going on at the U.S. Patent Office. It also reported on a broad range of inventions including perpetual motion machines, an 1860 device for buoying vessels by Abraham Lincoln, and the universal joint which now can be found in nearly every automobile manufactured. Current issues inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
