Canavanine

L-(+)-(S)-Canavanine is a non-proteinogenic amino acid found in certain leguminous plants. It is structurally related to the proteinogenic α-amino acid L-arginine, the sole difference being the replacement of a methylene bridge (-CH
2
- unit) in arginine with an oxa group (i.e., an oxygen atom) in canavanine. Canavanine is accumulated primarily in the seeds of the organisms which produce it, where it serves both as a highly deleterious defensive compound against herbivores and a vital source of nitrogen for the growing embryo[1] (see also L-canaline). The mechanism of canavanine's toxicity is that organisms that consume it typically mistakenly incorporate it into their own proteins in place of L-arginine, thereby producing structurally aberrant proteins that may not function properly.

Can-Arg
Chemical structure of canavanine compared to arginine

Some specialized herbivores tolerate L-canavanine either because they metabolize it efficiently (cf. L-canaline) or avoid its incorporation into their own nascent proteins. An example of this ability can be found in the larvae of the tobacco budworm Heliothis virescens, which can tolerate massive amounts of dietary canavanine. These larvae fastidiously avoid incorporation of L-canavanine into their nascent proteins (presumably by virtue of highly discriminatory Arginine—tRNA ligase, the enzyme responsible for the first step in the incorporation of arginine into proteins). In contrast, larvae of the tobacco hornworm Manduca sexta can only tolerate tiny amounts (1.0 microgram per kilogram of fresh body weight[2]) of dietary canavanine because their arginine-tRNA ligase has little, if any, discriminatory capacity. No one has examined experimentally the arginine-tRNA synthetase of these organisms. But comparative studies of the incorporation of radiolabeled L-arginine and L-canavanine have shown that in Manduca sexta, the ratio of incorporation is about 3 to 1.

Dioclea megacarpa seeds contain high levels of canavanine. The beetle Caryedes brasiliensis is able to tolerate this however as it has the most highly discriminatory arginine-tRNA ligase known. In this insect, the level of radiolabeled L-canavanine incorporated into newly synthesized proteins is barely measurable. Moreover, this beetle uses canavanine as a nitrogen source to synthesize its other amino acids to allow it to develop.[3]

NZB/W F1, NZB, and DBA/2 mice fed L-canavanine develop a syndrome similar to systemic lupus erythematosus,[4] while BALB/c mice fed a steady diet of protein containing 1% canavanine showed no change in lifespan.[5] The toxicity of canavanine may be enhanced under conditions of protein starvation,[4] and canavanine toxicity resulting from consumption of Hedysarum alpinum seeds, which contain quantities of canavanine around 1%, has been implicated in the death of Christopher McCandless.[6]

Alfalfa seeds and sprouts contain L-canavanine. The L-canavanine in alfalfa has been linked to lupus-like symptoms in primates, including humans, and other auto-immune diseases. Often stopping consumption reverses the problem.[7][8][9]

Canavanine
Chemical structure of L-(+)-(S)-canavanine
Names
Preferred IUPAC name
Canavanine
Systematic IUPAC name
(2S)-2-amino-4-{[(diaminomethylidene)amino]oxy}butanoic acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.153.281
KEGG
MeSH Canavanine
Properties
C5H12N4O3
Molar mass 176.176 g·mol−1
Density 1.61 g·cm−3 (predicted)
Melting point 184 °C (363 °F; 457 K)
Boiling point 366 °C (691 °F; 639 K)
soluble
Solubility insoluble in alcohol, ether, benzene
log P -0.91 (predicted)
Vapor pressure 1.61 μPa (predicted)
Hazards
Flash point 214.6 °C (418.3 °F; 487.8 K) (predicted)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

See also

References

  1. ^ "Non-protein amino acids (NPA)". January 2009. Archived from the original on 2011-01-22. Retrieved 2011-01-22.
  2. ^ Rosenthal, G. A.; Dahlman, D. L. (1986). "L-Canavanine and protein synthesis in the tobacco hornworm Manduca sexta". Proceedings of the National Academy of Sciences. 83 (1): 14–8. Bibcode:1986PNAS...83...14R. doi:10.1073/pnas.83.1.14. JSTOR 26787. PMC 322781. PMID 3455753.
  3. ^ Rosenthal, G. A.; Hughes, C. G.; Janzen, D. H. (1982). "L-Canavanine, a Dietary Nitrogen Source for the Seed Predator Caryedes brasiliensis (Bruchidae)". Science. 217 (4557): 353–5. Bibcode:1982Sci...217..353R. doi:10.1126/science.217.4557.353. PMID 17791516.
  4. ^ a b Akaogi, Jun; Barker, Tolga; Kuroda, Yoshiki; Nacionales, Dina C.; Yamasaki, Yoshioki; Stevens, Bruce R.; Reeves, Westley H.; Satoh, Minoru (2006). "Role of non-protein amino acid l-canavanine in autoimmunity". Autoimmunity Reviews. 5 (6): 429–35. doi:10.1016/j.autrev.2005.12.004. PMID 16890899.
  5. ^ Brown, Dan L (2005). "Canavanine-induced longevity in mice may require diets with greater than 15.7% protein". Nutrition & Metabolism. 2 (1): 7. doi:10.1186/1743-7075-2-7. PMC 554090. PMID 15733319.
  6. ^ Krakauer, Jon. "How Chris McCandless Died: An Update". The New Yorker. Retrieved 12 February 2015.
  7. ^ Montanaro, A; Bardana Jr, E. J. (1991). "Dietary amino acid-induced systemic lupus erythematosus". Rheumatic diseases clinics of North America. 17 (2): 323–32. PMID 1862241.
  8. ^ Herbert, V; Kasdan, T. S. (1994). "Alfalfa, vitamin E, and autoimmune disorders". The American Journal of Clinical Nutrition. 60 (4): 639–40. PMID 8092103.
  9. ^ http://vegpeace.org/rawfoodtoxins.html

Bibliography

  • Rosenthal, Gerald A. (1986). "Biochemical insight into insecticidal properties ofl-Canavanine, a higher plant protective allelochemical". Journal of Chemical Ecology. 12 (5): 1145–56. doi:10.1007/BF01639001. PMID 24307052.
  • Rosenthal, G. A.; Berge, M. A.; Bleiler, J. A.; Rudd, T. P. (1987). "Aberrant, canavanyl protein formation and the ability to tolerate or utilize L-canavanine". Experientia. 43 (5): 558–61. doi:10.1007/BF02143585. PMID 3582574.
Alfalfa

Alfalfa (), also called lucerne and called Medicago sativa in binomial nomenclature, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as well as a green manure and cover crop. The name alfalfa is used in North America. The name lucerne is the more commonly used name in the United Kingdom, South Africa, Australia, and New Zealand. The plant superficially resembles clover (a cousin in the same family), especially while young, when trifoliate leaves comprising round leaflets predominate. Later in maturity, leaflets are elongated. It has clusters of small purple flowers followed by fruits spiralled in 2 to 3 turns containing 10–20 seeds. Alfalfa is native to warmer temperate climates. It has been cultivated as livestock fodder since at least the era of the ancient Greeks and Romans. Alfalfa sprouts are a common ingredient in dishes made in South Indian cuisine.

Alkyl nitrites

Alkyl nitrites are a group of chemical compounds based upon the molecular structure R-ONO. Formally they are alkyl esters of nitrous acid. They are distinct from nitro compounds (R-NO2).

The first few members of the series are volatile liquids; methyl nitrite and ethyl nitrite are gaseous at room temperature and pressure. The compounds have a distinctive fruity odor. Another frequently encountered nitrite is amyl nitrite (3-methylbutyl nitrite).

Alkyl nitrites were initially, and largely still are used as medications and chemical reagents, a practice which began in the late 19th century. In their use as medicine, are often inhaled for relief of angina and other heart-related symptoms of disease. However, when referred to as "poppers", alkyl nitrites represent recreational drugs.

Butyl nitrite

Butyl nitrite is an alkyl nitrite made from n-butanol. Butyl nitrite is used recreationally as poppers.

Canaline

L-Canaline (IUPAC name 2-amino-4-(aminooxy)butyric acid)) is a non-proteinogenic amino acid. The compound is found in legumes that contain canavanine, from which it is produced by the action of arginase. The most common-used source for this amino acid is the jack bean, Canavalia ensiformis.

L-Canaline is the only naturally occurring amino acid known that has an O-alkyl hydroxylamine functionality in the side chain. This amino acid is structurally related to ornithine (it is the 5-oxa derivative) and is a potent insecticide. Tobacco hornworm larvae fed a diet containing 2.5 mM canaline showed massive developmental aberrations, and most larvae so treated died at the pupal stage. It also exhibits potent neurotoxic effects in the moth.

Its toxicity stems primarily from the fact that it readily forms oximes with keto acids and aldehydes, especially the pyridoxal phosphate cofactor of many vitamin B6-dependent enzymes. It inhibits ornithine aminotransferase at concentrations as low as 10 nM.

L-Canaline is a substrate for ornithine aminotransferase resulting in the synthesis of L-ureidohomoserine (the corresponding analog of L-citrulline). In turn, the latter forms L-canavaninosuccinic acid in a reaction mediated by argininosuccinic acid synthetase. L-Canavaninosuccinic acid is cleaved to form L-canavanine by argininosuccinic acid synthetase. By these sequential reactions, the canaline-urea cycle (analogous to the ornithine-urea cycle) is formed. Every time a canavanine molecule runs through the canaline-urea cycle, the two terminal nitrogen atoms are released as urea. Urea is an important by-product of this reaction sequence because it makes ammonicial ammonia (urease-mediated) that is available to support intermediary nitrogen metabolism. L-Canaline can be reductively cleaved to L-homoserine, a non-protein amino acid of great importance in the formation of a host of essential amino acids. In this way, the third nitrogen atom of canavanine enters into the reactions of nitrogen metabolism of the plant. As homoserine, its carbon skeleton also finds an important use.

Chris McCandless

Christopher Johnson McCandless (; February 12, 1968 – c. August 1992) was an American hiker and itinerant traveler, who also went by the name "Alexander Supertramp". After graduating from college in 1990, McCandless traveled across the North American continent and eventually hitchhiked to Alaska in April 1992. There, he set out along an old mining road known as the Stampede Trail, with minimal supplies, hoping to live simply off the land. In September, McCandless' decomposing body, weighing only 30 kilograms (66 lb), was found by a hunter in a converted bus, Fairbanks Bus 142, used as a backcountry shelter along the Stampede Trail, on the eastern bank of the Sushana River. His cause of death was officially ruled to be starvation, although the exact cause remains the subject of some debate.In January 1993, Jon Krakauer published McCandless' story in that month's issue of Outside magazine. He had been assigned the story and had written it under a tight deadline. Inspired by the details of McCandless' story, Krakauer wrote and published the more extensive biographical book Into the Wild (1996), about McCandless' travels. The book was subsequently adapted into a 2007 film directed by Sean Penn, with Emile Hirsch portraying McCandless. That same year, McCandless' story also became the subject of Ron Lamothe's documentary The Call of the Wild (2007).

Cinaciguat

Cinaciguat (BAY 58-2667) is an experimental drug for the treatment of acute decompensated heart failure.

Hedysarum alpinum

Hedysarum alpinum is a species of flowering plant in the legume family known by the common name alpine sweetvetch. It has a circumpolar distribution, occurring throughout the northern latitudes of the Northern Hemisphere. In North America it is widespread in Canada and the northernmost United States, including Alaska.This plant is a perennial herb producing several erect stems from its caudex. It grows to 70 centimetres (28 inches) in height. The taproot is thick and woody, and it has rhizomes which can produce new stems. The leaves are each divided into a number of leaflets up to 3.5 centimetres (1.4 inches) long. The inflorescence is a dense raceme of flowers. The flowers are pink or pale purple and up to 1.5 centimetres (0.59 inches) long. The flowers are pollinated by insects such as the bumblebee and honeybee. The fruit is a flat legume pod which is narrowed between the seeds, with as many as 9 segments.This plant generally grows in the boreal and northern temperate climates. It occurs in tundra and taiga habitat types, in floodplains, grasslands, and dry forests. It is well adapted to calcareous soils. It is usually not a dominant species but it is considered dominant in several river deltas and plains in Alaska. It is a pioneer species on floodplains that have been recently scoured by water and ice. It grows with willows and birches along waterways and in forests dominated by spruces. It grows on grasslands with grass species such as little bluestem (Schizachyrium scoparium), Canada bluegrass (Poa compressa), and American dunegrass (Leymus mollis).Alpine sweetvetch is an important source of food for many types of animals, including black bears, grizzly bears, American bison, moose, Dall's sheep, and caribou. Bears are adept at digging up the nutritious roots. The roots are a primary food for grizzly bears in some areas, such as Banff National Park. In parts of Alaska this plant is a primary food for Dall's sheep and caribou. Many small mammals, such as voles and short-tailed weasels eat it, and a variety of birds nest in alpine sweetvetch habitat.Native Alaskan peoples used and still use the plant for food, particularly the fleshy roots. The roots are said to taste like young carrots. The Inupiat people call the plant wild potato and obtain dietary fiber from the roots. Alpine sweetvetch is the most important food source for the Dena'ina people after wild fruit species. The Eskimo train dogs to locate stores of roots that have been cached by mice. The roots may be eaten raw or prepared in a number of ways, including boiling, roasting, and frying in grease. They are stored in lard or oil and eaten when other food stores run out. The seeds should not be eaten raw, or in large quantity, as they contain L-canavanine, which may have led or contributed to the death of Christopher McCandless.

Isopropyl nitrite

The chemical compound isopropyl nitrite (or 2-propyl nitrite) is an alkyl nitrite made from isopropanol. It is a clear pale yellow oil.

Itramin tosilate

Itramin tosilate (itramin tosylate) is a vasodilator.

List of MeSH codes (D12.125)

This is part of the list of the "D" codes for MeSH. It is a product of the United States National Library of Medicine.

Source for content is here. (File "2006 MeSH Trees".)

Nipradilol

Nipradilol is a beta blocker and nitric oxide donor.

Nitric oxide synthase 2 (inducible)

Nitric oxide synthase, inducible is an enzyme that in humans is encoded by the NOS2 gene.Nitric oxide is a reactive free radical which acts as a biologic mediator in several processes, including neurotransmission and antimicrobial and antitumoral activities. This gene encodes a nitric oxide synthase which is expressed in the liver and is inducible by a combination of lipopolysaccharide and certain cytokines. Three related pseudogenes are located within the Smith-Magenis syndrome region on chromosome 17. Alternative splicing of this gene results in two transcript variants encoding different isoforms.

Non-protein amino acid-accumulating clade

The non-protein amino acid-accumulating clade is a monophyletic clade of the flowering plant subfamily Faboideae (or Papilionoideae) that includes the majority of agriculturally-cultivated legumes. It is characterized by the accumulation of canavanine in the seeds—a deterrent against herbivory. This phylogenetic trait was first recognized in the early 1980s. This clade is consistently resolved in molecular phylogenies. It contains many economically important genera, including Cicer, Glycine, Medicago, Phaseolus, Trifolium, Vicia, and Vigna.

Propatylnitrate

Propatylnitrate (propatyl nitrate) is a nitrate.

Proteinogenic amino acid

Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms.In contrast, non-proteinogenic amino acids are amino acids that are either not incorporated into proteins (like GABA, L-DOPA, or triiodothyronine), misincorporated in place of a genetically encoded amino acid, or not produced directly and in isolation by standard cellular machinery (like hydroxyproline). The latter often results from post-translational modification of proteins. Some non-proteinogenic amino acids are incorporated into nonribosomal peptides which are synthesized by non-ribosomal peptide synthetases.

Both eukaryotes and prokaryotes can incorporate selenocysteine into their proteins via a nucleotide sequence known as a SECIS element, which directs the cell to translate a nearby UGA codon as selenocysteine (UGA is normally a stop codon). In some methanogenic prokaryotes, the UAG codon (normally a stop codon) can also be translated to pyrrolysine.In eukaryotes, there are only 21 proteinogenic amino acids, the 20 of the standard genetic code, plus selenocysteine. Humans can synthesize 12 of these from each other or from other molecules of intermediary metabolism. The other nine must be consumed (usually as their protein derivatives), and so they are called essential amino acids. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine (i.e. H, I, L, K, M, F, T, W, V).The proteinogenic amino acids have been found to be related to the set of amino acids that can be recognized by ribozyme autoaminoacylation systems. Thus, non-proteinogenic amino acids would have been excluded by the contingent evolutionary success of nucleotide-based life forms. Other reasons have been offered to explain why certain specific non-proteinogenic amino acids are not generally incorporated into proteins; for example, ornithine and homoserine cyclize against the peptide backbone and fragment the protein with relatively short half-lives, while others are toxic because they can be mistakenly incorporated into proteins, such as the arginine analog canavanine.

Sprouting

Sprouting is the natural germination process by which seeds or spores put out shoots, plants produce new leaves or buds, or other newly developing parts experience further growth.

In the field of nutrition, the term signifies the practice of germinating seeds, to be eaten raw or cooked.

The term can also be used for hair growth, and in a figurative sense it can mean something appearing suddenly.

Tenitramine

Tenitramine (trade name Tinitran) is a nitrovasodilator.

Trolnitrate

Trolnitrate is a nitrate.

Vicia

Vicia is a genus of about 140 species of flowering plants that are part of the legume family (Fabaceae), and which are commonly known as vetches. Member species are native to Europe, North America, South America, Asia and Africa. Some other genera of their subfamily Faboideae also have names containing "vetch", for example the vetchlings (Lathyrus) or the milk-vetches (Astragalus). The broad bean (Vicia faba) is sometimes separated in a monotypic genus Faba; although not often used today, it is of historical importance in plant taxonomy as the namesake of the order Fabales, the Fabaceae and the Faboideae. The tribe Vicieae in which the vetches are placed is named after the genus' current name. Among the closest living relatives of vetches are the lentils (Lens) and the true peas (Pisum).

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