Catalyzes the reduction of both Delta(1)-pyrroline-2-carboxylate (Pyr2C) and Delta(1)-piperideine-2-carboxylate (Pip2C) to L-proline and L-pipecolate, respectively, using NADPH as the electron donor. Can use NADH instead of NADPH, although with much less efficiency. Plays an essential role in the catabolism of D-proline and D-lysine, which allows P.putida to grow on each of these amino-acids as a sole carbon source; D-lysine appears to be catabolized only through the pipecolate pathway. Can also catalyze the reverse oxidation reactions, albeit at a much lower rate. To a lesser extent, is able to catalyze in vitro the NADPH-dependent formation of N-alkyl-L-amino acids from the corresponding alpha-oxo acids and alkylamines, e.g. the formation of N-methylalanine from pyruvate and N-methylamine; cannot use ammonia as substrate for these reductive amination reactions. Shows neither malate dehydrogenase nor lactate dehydrogenase activity. L-pipecolate + NADP(+) = Delta(1)-piperideine-2-carboxylate + H(+) + NADPH L-proline + NADP(+) = 1-pyrroline-2-carboxylate + H(+) + NADPH H2O + N-methyl-L-alanine + NADP(+) = H(+) + methylamine + NADPH + pyruvate Is inhibited by the substrate analog pyrrole-2-carboxylate, but not by N-formylphenylalanine. Optimum pH is 7.0 for Pyr2C reduction, 8.0 for Pip2C reduction, and 10.0 for L-proline and L-pipecolate oxidation. Optimum temperature is 35 degrees Celsius. Is inactivated at a rate of about a 30% decrease in 30 minutes at 35 degrees Celsius. The enzyme keeps its full activity, however, at 30 degrees Celsius for at least 30 minutes. Homodimer. Cells lacking this gene loss their ability to grow on D-lysine and also on D-proline as a sole carbon source. Moreover, the mutant strain grows only slowly in the medium containing L-lysine as a sole carbon source in contrast to the wild-type strain. No difference is evident between the two strains in other media containing as a sole carbon source L-pipecolate, L-proline, and the following D-amino acids: D-alanine, D-valine, D-leucine, D-isoleucine, D-serine, D-threonine, D-aspartate, D-glutamate, D-glutamine, D-arginine, and D-phenylalanine. The enzyme reaction proceeds through an ordered Bi-Bi mechanism. Belongs to the LDH2/MDH2 oxidoreductase family.