Catalyzes the dehydration of trans-3-hydroxy-L-proline (t3LHyp) to Delta(1)-pyrroline-2-carboxylate (Pyr2C) in vitro. Displays no proline racemase activity. trans-3-hydroxy-L-proline = 1-pyrroline-2-carboxylate + H2O kcat is 4.1 sec(-1) for t3LHyp dehydration. Belongs to the proline racemase family.