Canavanine
 |
|
| Names | |
|---|---|
|
Preferred IUPAC name
Canavanine
|
|
|
Systematic IUPAC name
(2S)-2-amino-4-{[(diaminomethylidene)amino]oxy}butanoic acid
|
|
| Identifiers | |
|
3D model (Jmol)
|
|
| ChEBI | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.153.281 |
| KEGG | |
| MeSH | Canavanine |
|
PubChem CID
|
|
|
|
|
|
| Properties | |
| C5H12N4O3 | |
| Molar mass | 176.18 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).
|
|
| Infobox references | |
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 (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.
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) 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.
...
Wikipedia