Canaline

Canaline is a non-proteinogenic amino acid that is found in certain legumes. It is a derivative of ornithine, a non-essential amino acid that plays a role in the urea cycle. Canaline is notable for its role in the biosynthesis of canavanine, a toxic amino acid that is used by some plants as a defense mechanism against herbivores.

Structure and Properties

Canaline is a guanidino compound, which means it contains a functional group that consists of a carbon atom double-bonded to a nitrogen atom and single-bonded to two other nitrogen atoms. This structure is similar to that of arginine, another amino acid.

The molecular formula of canaline is C5H12N4O2, and its molecular weight is 160.18 g/mol. It is a white, crystalline solid that is soluble in water.

Biosynthesis

Canaline is synthesized from ornithine in a two-step process. First, ornithine is converted to N-acetylornithine by the enzyme ornithine acetyltransferase. Then, N-acetylornithine is converted to canaline by the enzyme canaline synthase.

Role in Canavanine Biosynthesis

Canaline serves as a precursor in the biosynthesis of canavanine. The conversion of canaline to canavanine is catalyzed by the enzyme canavanine synthase. This reaction involves the transfer of a cyanide group from cyanophosphate to canaline.

Toxicity

Canaline itself is not toxic, but it can be converted into the toxic amino acid canavanine in the body. Therefore, consumption of plants that contain high levels of canaline can lead to canavanine poisoning. Symptoms of canavanine poisoning include nausea, vomiting, and diarrhea. In severe cases, it can cause liver damage and kidney failure.

See Also

• Non-proteinogenic amino acids
• Ornithine
• Canavanine
• Cyanophosphate