| Section2 = | Section3 = }} Proline (abbreviated as Pro or P)'s an α-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It isn't an essential amino acid, which means that humans can synthesize it. It's unique among the 20 protein-forming amino acids because the α-amino group's secondary. Biosynthesis Proline's biosynthetically derived from the amino acid L-glutamate and its immediate precursor's the imino acid (S)-1-pyrroline-5-carboxylate… (More on Proline)