Canavanine (CVN)

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 in arginine with an oxa group 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. 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 efficientlyor avoid its incorporation into their own nascent proteins.