Glycine is degraded through three pathways: The glycine cleavage system (GCS); by serine hydroxymethyltransferase, and conversion to glyoxylate. In animals, the main pathway is GCS, which is essentially the reverse of the glycine synthase pathway.
Degradation of by serine hydroxymethyltransferase happens in two steps. First, glycine is converted to serine by serine hydroxymethyl transferase. Serine is then converted to pyruvate by serine dehydratase.
Glycine can also be converted to glyoxylate by D-amino acid oxidase. Glyoxylate is then oxidized by hepatic lactate dehydrogenase to oxalate.
Description adapted from [Wikipedia](https://en.wikipedia.org/wiki/Glycine#Metabolism).