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Awara |
| Synonyms:
Canavalia ensiformis (L.) DC. Var. albida DC. Canavalia
ensiformis (L.)DC. Var. truncata Ricker, Canavalia gladiata (Jacq.)DC.
Var. leucosperma Voigt, Dolichos acinaciformis Jacq. Dolichos ensiformis L. |
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| Vernacular Name: Sinhala: Awara; Eng: Jack bean, Sword bean, Giant stock-bean, Wonder bean. | |
| Description: Pods reach a length of 10-14 inches, and a width of 1 to 1½ inches. Seeds are large, ½-¾ inch long and nearly as broad. The two species differ mainly in the length of the seed hilum (scar). The hilum the jack bean is only about one-third as long as the seed. Most of the jack beans identified in Gainesville have been white with a black seed scar, while the sword beans have been red seeded. | |
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| Chemical Constituents: Canatoxin is a toxic protein from Canavalia ensiformis seeds, lethal to mice (LD(50)=2 mg/kg) and insects. Further characterization of canatoxin showed that its main native form (184 kDa) is a non-covalently linked dimer of a 95 kDa polypeptide containing zinc and nickel. Partial sequencing of internal peptides indicated homology with urease (EC 3.5.1.5) from the same seed. Canatoxin has approx. 30% of urease's activity for urea, and K(m) of 2-7 mM. The proteins differ in their affinities for metal ions and were separated by affinity chromatography on a Zn(2+) matrix. Similar to canatoxin, urease activates blood platelets and interacts with glycoconjugates. In contrast with canatoxin, no lethality was seen in mice injected with urease (10 mg/kg). Pretreatment with p-hydroxymercuribenzoate irreversibly abolished the ureolytic activity of both proteins. On the other hand, p-hydroxymercuribenzoate-treated canatoxin was still lethal to mice, and both treated proteins were fully active in promoting platelet aggregation and binding to glycoconjugates. Taken together, our data indicate that canatoxin is a variant form of urease. Moreover, we show for the first time that these proteins display several biological effects that are unrelated to their enzymic activity for urea. | |
| Uses: reported to be edible in the young tender immature stage by slicing and boiling the tender pods, or peeling and using the seeds as broad beans. Also, have indicated the possibility of mild toxicity of beans when eaten in large quantities. Because of this, the boiling water should be drained off to remove any poisonous substances coming from the beans. Pharmaceutical companies have shown some interest in the beans as a possible source of the enzyme urease, and a few acres have been tried in Florida for that purpose. | |
