DL-Proline is used as an agonist of glycine receptors. It acts as a catalyst for aldol condensation. It is an essential component of collagen. It plays a significant role in the immune system and strengthening of heart muscles. It is an osmoprotectant and therefore is used in many pharmaceutical, biotechnological applications.
Serb, M.; Englert, U. Unexpected proline coordination in the copper chain polymer [Cu([mu]-Cl)2([mu]-dl-proline-[kappa]2O:O')]1[infinity]. Acta Crystallogr. Sect. C-Cryst. Struct. Commun. 2015, 71 (4), 271-275.
Tan, H.; Liu, H.; Chen, X.; Chen, H.; Qiu, S. Racemic total synthesis of dactyloidin and demethyldactyloidin through the dl-proline-catalyzed Knoevenagel condensation/[4+ 2] cycloaddition cascade. Org. Biomol. Chem. 2015, 13 (39), 9977-9983.