sentences:  In many prokaryotes, proline dehydrogenase and P5C dehydrogenase form a bifunctional enzyme that prevents the release of P5C during proline degradation.In arginine degradation, the enzyme ornithine-δ-aminotransferase mediates the transamination between ornithine and a 2-oxo acid (typically α-ketoglutarate) to form P5C and an L-amino acid (typically glutamate).Under specific conditions, P5C may also be used for arginine biosynthesis via the reverse reaction of ornithine-δ-aminotransferase.