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<small>L</small>-(+)-(''S'')-'''Canavanine''' is a [[Non-proteinogenic amino acid|non-proteinogenic]] [[amino acid|α-amino acid]] found in certain [[legume|leguminous plants]]. It is structurally related to the [[Proteinogenic amino acid|proteinogenic]] α-amino acid <small>L</small>-[[arginine]], the sole difference being the replacement of a [[methylene bridge]] (-{{chem|CH|2}}- unit) in arginine with an oxa group (i.e., an [[oxygen]] atom) in canavanine. Canavanine is accumulated primarily in the [[seed]]s 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<ref>{{cite web | url = http://www.biologie.uni-freiburg.de/data/bio3/igloi/Accuracy.htm | title = Non-protein amino acids (NPA) | accessdate = 2011-01-22 | date = January 2009 | archiveurl = http://www.webcitation.org/5vv9QlDjo | archivedate = 2011-01-22}}</ref> (see also <small>L</small>-[[canaline]]). The mechanism of canavanine's toxicity is that organisms that consume it typically mistakenly incorporate it into their own [[protein]]s in place of <small>L</small>-arginine, thereby producing structurally aberrant proteins that may not function properly.
<small>L</small>-(+)-(''S'')-'''Canavanine''' is a [[Non-proteinogenic amino acid|non-proteinogenic]] [[amino acid|α-amino acid]] found in certain [[legume|leguminous plants]]. It is structurally related to the [[Proteinogenic amino acid|proteinogenic]] α-amino acid <small>L</small>-[[arginine]], the sole difference being the replacement of a [[methylene bridge]] (-{{chem|CH|2}}- unit) in arginine with an oxa group (i.e., an [[oxygen]] atom) in canavanine. Canavanine is accumulated primarily in the [[seed]]s 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<ref>{{cite web | url = http://www.biologie.uni-freiburg.de/data/bio3/igloi/Accuracy.htm | title = Non-protein amino acids (NPA) | accessdate = 2011-01-22 | date = January 2009 | archiveurl = http://www.webcitation.org/5vv9QlDjo | archivedate = 2011-01-22}}{{self-published inline}}</ref> (see also <small>L</small>-[[canaline]]). The mechanism of canavanine's toxicity is that organisms that consume it typically mistakenly incorporate it into their own [[protein]]s in place of <small>L</small>-arginine, thereby producing structurally aberrant proteins that may not function properly.


[[File:Can-Arg.svg|thumb|left|alt=Side-by-side comparison of the structures of arginine and canavanine, with the difference highlighted|Chemical structure of arginine compared to canavanine]]
[[File:Can-Arg.svg|thumb|left|alt=Side-by-side comparison of the structures of arginine and canavanine, with the difference highlighted|Chemical structure of arginine compared to canavanine]]


Some specialized herbivores tolerate <small>L</small>-canavanine either because they metabolize it efficiently (cf. <small>L</small>-canaline) or avoid its incorporation into their own nascent proteins. An example of this ability can be found in the [[tobacco budworm]] ''[[Heliothis]] [[Heliothis virescens|virescens]]'' the larvae of which can tolerate massive amounts of dietary canavanine. These larvae fastidiously avoid incorporation of <small>L</small>-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]] [[Manduca sexta|sexta]]'' can only tolerate tiny amounts (1.0 microgram per kilogram of fresh body weight<ref name='Rostenthal19860101'>{{cite journal | doi = 10.1073/pnas.83.1.14 | title = L-Canavanine and protein synthesis in the tobacco hornworm ''Manduca sexta'' | journal = Proc Natl Acad Sci U S A | date = 1986-01-01 | last1 = Rosenthal | first1 = G .A. | last2 = Dahlman | first2 = D. L. | volume = 83 | issue = 1 | pages = 14–18 | pmid = 3455753 | pmc = 322781 | url = http://www.pnas.org/content/83/1/14.abstract | accessdate = 2011-01-22 }}</ref>) of dietary canavanine because their arginine-[[transfer RNA|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 <small>L</small>-arginine and <small>L</small>-canavanine have shown that in ''Manduca sexta'', the ratio of incorporation is about 3 to 1.
Some specialized herbivores tolerate <small>L</small>-canavanine either because they metabolize it efficiently (cf. <small>L</small>-canaline) or avoid its incorporation into their own nascent proteins. An example of this ability can be found in the [[tobacco budworm]] ''[[Heliothis]] [[Heliothis virescens|virescens]]'' the larvae of which can tolerate massive amounts of dietary canavanine. These larvae fastidiously avoid incorporation of <small>L</small>-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]] [[Manduca sexta|sexta]]'' can only tolerate tiny amounts (1.0 microgram per kilogram of fresh body weight<ref name='Rostenthal19860101'>{{cite journal |doi=10.1073/pnas.83.1.14}}</ref>) of dietary canavanine because their arginine-[[transfer RNA|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 <small>L</small>-arginine and <small>L</small>-canavanine have shown that in ''Manduca sexta'', the ratio of incorporation is about 3 to 1.


''[[Dioclea]] [[Dioclea megacarpa|megacarpa]]'' seeds contain high levels of canavanine. The beetle ''[[Bruchinae|Caryedes]] [[Caryedes brasiliensis|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 <small>L</small>-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.<ref name='Rosenthal19820723'>{{cite journal | title = L-Canavanine, a Dietary Nitrogen Source for the Seed Predator ''Caryedes brasiliensis'' (Bruchidae) | journal = Science | date = 1982-07-23 | first1 = Gerald A. | last1 = Rosenthal | first2 = Charlie G. | last2 = Hughes | first3 = Daniel H. | last3 = Janzen | volume = 217 | issue = 4557 | pages = 353–355 | doi = 10.1126/science.217.4557.353 | pmid = 17791516 | url = http://www.sciencemag.org/content/217/4557/353.abstract | accessdate = 2011-01-22}}</ref>
''[[Dioclea]] [[Dioclea megacarpa|megacarpa]]'' seeds contain high levels of canavanine. The beetle ''[[Bruchinae|Caryedes]] [[Caryedes brasiliensis|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 <small>L</small>-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.<ref name='Rosenthal19820723'>{{cite journal |doi=10.1126/science.217.4557.353}}</ref>


NZB/W F1, NZB, and DBA/2 mice fed L-canavanine develop an SLE-like syndrome,<ref name="ncbi.nlm.nih.gov">http://www.ncbi.nlm.nih.gov/pubmed/16890899</ref> while BALB/c mice fed a steady diet of protein containing 1% canavanine showed no change in lifespan.<ref>http://www.ncbi.nlm.nih.gov/pubmed/15733319</ref> The toxicity of canavanine may be enhanced under conditions of protein starvation,<ref name="ncbi.nlm.nih.gov"/> 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]].<ref>{{cite web | url=http://www.newyorker.com/books/page-turner/chris-mccandless-died-update | title=How Chris McCandless Died: An Update | work=The New Yorker | accessdate=12 February 2015 | author=Krakauer, Jon}}</ref>
NZB/W F1, NZB, and DBA/2 mice fed L-canavanine develop an SLE-like syndrome,<ref name=pmid16890899>{{cite journal |doi=10.1016/j.autrev.2005.12.004}}</ref> while BALB/c mice fed a steady diet of protein containing 1% canavanine showed no change in lifespan.<ref>{{cite journal |doi=10.1186/1743-7075-2-7}}</ref> The toxicity of canavanine may be enhanced under conditions of protein starvation,<ref name=pmid16890899/> 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]].<ref>{{cite web | url=http://www.newyorker.com/books/page-turner/chris-mccandless-died-update | title=How Chris McCandless Died: An Update | work=The New Yorker | accessdate=12 February 2015 | author=Krakauer, Jon}}</ref>


[[Alfalfa]] seeds and sprouts contain <small>L</small>-canavanine. The <small>L</small>-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.<ref>http://www.ncbi.nlm.nih.gov/pubmed/1862241</ref><ref>http://ajcn.nutrition.org/content/60/4/639.full.pdf</ref><ref>http://vegpeace.org/rawfoodtoxins.html</ref>
[[Alfalfa]] seeds and sprouts contain <small>L</small>-canavanine. The <small>L</small>-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.<ref>{{cite journal |pmid=1862241}}</ref><ref>{{cite journal |pmid=8092103 |url=http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=8092103}}{{MEDRS}}</ref><ref>http://vegpeace.org/rawfoodtoxins.html{{full}}{{MEDRS}}</ref>


==See also==
==See also==
Line 52: Line 52:


== Bibliography ==
== Bibliography ==
*{{cite journal |doi=10.1007/BF01639001}}
* {{cite journal | title = Biochemical insight into insecticidal properties of L-Canavanine, a higher plant protective allelochemical | journal = Journal of Chemical Ecology | year = 1986 | first = Gerald A. | last = Rosenthal | volume = 12 | issue = 5 | pages = 1145–1156 | doi = 10.1007/BF01639001 | url = http://www.springerlink.com/content/xn667qp842871175/ | accessdate = 2011-01-22}}
* {{cite journal |doi=10.1007/BF02143585}}
* {{cite journal | title = Aberrant, canavanyl protein formation and the ability to tolerate or utilize L-canavanine | journal = Experientia | date = 1987-05-15 | first1 = G. A. | last1 = Rosenthal | first2 = M. A. | last2 = Berge | first3 = J. A. | last3 = Bleiler | first4 = T. P. | last4 = Rudd | volume = 43 | issue = 5 | pages = 558–561 | doi = 10.1007/BF02143585 | pmid = 3582574 | url = http://www.springerlink.com/content/p707710081267665/ | accessdate = 2011-01-22}}


[[Category:Amino acids]]
[[Category:Amino acids]]

Revision as of 13:00, 18 February 2015

{{Chembox | ImageFile = L-S-Canavanine.svg | ImageName = Chemical structure of L-(+)-(S)-canavanine | PIN = Canavanine | SystematicName = (2S)-2-amino-4-{[(diaminomethylidene)amino]oxy}butanoic acid |Section1=! colspan=2 style="background: #f8eaba; text-align: center;" |Identifiers

|-

|

|

|-

|

3D model (JSmol)

|

|-


| ChEBI

|

|-

| ChemSpider

|

|- | DrugBank

|

|- | ECHA InfoCard | 100.153.281 Edit this at Wikidata |-



| KEGG

|

|- | MeSH | Canavanine |-

|

|

|-


|

|

|-

| colspan="2" |

  • InChI=1S/C5H12N4O3/c6-3(4(10)11)1-2-12-9-5(7)8/h3H,1-2,6H2,(H,10,11)(H4,7,8,9)/t3-/m0/s1

|-

| colspan="2" |

  • N[C@@H](CCON=C(N)N)C(O)=O

|- |Section2=! colspan=2 style="background: #f8eaba; text-align: center;" |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) |- |Section3=! colspan=2 style="background: #f8eaba; text-align: center;" |Hazards

|-


| Flash point | 214.6 °C (418.3 °F; 487.8 K)

|- }}

L-(+)-(S)-Canavanine is a non-proteinogenic α-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.

Side-by-side comparison of the structures of arginine and canavanine, with the difference highlighted
Chemical structure of arginine compared to canavanine

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 tobacco budworm Heliothis virescens the larvae of 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 an SLE-like syndrome,[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 ofHedysarum 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]

See also

References

  1. ^ "Non-protein amino acids (NPA)". January 2009. Archived from the original on 2011-01-22. Retrieved 2011-01-22.[self-published source?]
  2. ^ . doi:10.1073/pnas.83.1.14. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  3. ^ . doi:10.1126/science.217.4557.353. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  4. ^ a b . doi:10.1016/j.autrev.2005.12.004. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  5. ^ . doi:10.1186/1743-7075-2-7. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)CS1 maint: unflagged free DOI (link)
  6. ^ Krakauer, Jon. "How Chris McCandless Died: An Update". The New Yorker. Retrieved 12 February 2015.
  7. ^ . PMID 1862241. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  8. ^ . PMID 8092103 http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=8092103. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)[unreliable medical source?]
  9. ^ http://vegpeace.org/rawfoodtoxins.html[full citation needed][unreliable medical source?]

Bibliography

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