L-ornithine
(S)-2,5-diaminovaleric acid
(S)-2,5-Diaminopentanoic acid
(S)-2,5-Diaminopentanoato

C5H12N2O2

It's an amino acid.

Urea cycle (3D)
Catabolism of proline, histidine, arginine, glutamate and glutamine (3D)
Synthesis of glutamine, arginine, glutamate and proline (3D)
Alkaloid biosynthesis (Kyoto University)