| Compound | Description |
|---|---|
| hydronium ion | |
| ornithine | An amino acid produced in the urea cycle by the splitting off of urea from arginine. |
| Water | A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) |
| alpha-ketoglutaric acid |