Catalyzes the interconversion of L- and D-proline. Secreted isoform 1 contributes to parasite immune evasion by acting as a B-cell mitogen. Probably involved in parasite differentiation and infectivity. L-proline = D-proline Inhibited by maleic acid, iodoacetamide, iodoacetate and, most particularly, pyrrole-2-carboxylic acid. Optimum pH is 5.5-7.0. Homodimer. Membrane-bound and secreted upon differentiation of the parasite into non-dividing infective forms, suggesting that isoform 1 appears upon differentiation (PubMed:16164548). Cytoplasmic in replicative non-infective forms (PubMed:16164548). Belongs to the proline racemase family.