L-Ornithine is a not encoded by DNA. It is a free amino acid but do not participate in the protein synthesis. It is formed by the action of the enzyme arginase on L-arginine in the process of forming urea. It is implicated in the reduction of blood ammonia level and improves the efficiency of energy production to cause ammonia detoxification.
[1] L-ornithine promotes the release of growth hormone by triggering the pituitary gland.
[2]