Transaminase, which interconverts alpha-amino acids and alpha-keto acids, is a crucial enzyme within a number of contexts, including shuttline nitrogens from amino acid degradation to the urea cycle. Try to follow the mechanism in both the forward and reverse direction.

The deamination of amino acids yields keto acids such as pyruvic acid, which can ultimately be converted to carbohydrates or triglycerides. The amine groups are ultimately fated to form ammonia, urea, or uric acid. Animals with the need to conserve water carry the conversion all the way to uric acid. Guano is mostly uric-acid crystals.