Catabolism of L-canavanine and L-Canaline in the jack bean, Canavalia ensiformis (L.) DC. (leguminosae)

The metabolism of L-canavanine and its primary metabolite L-canaline was investigated in the jack bean, Canavalia ensiformis (L.) DC. (Leguminosae). L-[1,2,3,4-14C]Canavanine and L-[U-14C]canaline were synthesized from L-[U-14C]homoserine. After 1.5 h, 35% of the administered radiolabeled canaline was converted to acetone-soluble products; this amount decreased with time to 5.3% at 12 h. This fraction was primarily responsible for respiratory loss of 14C and 14CO2, which reached 52% of the administered canaline after 12 h. The water-soluble, neutral fraction accounted for no more than 10% of the injected canaline. The water soluble, charged materials contained 35-40% of the 14C at each time period; five compounds were identified within this fraction. They are homoserine, phosphohomoserine, lysine, canavanine, and canaline glyoxylate oxime. Canavanine-administered plants provided a degradation pattern remarkably similar to that of canaline-administered plants, indicating the importance of arginase-mediated hydrolysis of canavanine to canaline in the process of canavanine catabolism