Converts proline to delta-1-pyrroline-5-carboxylate (PubMed:17344208, PubMed:18426222). Has significant activity against O(2) producing superoxide during proline oxidation catalytic cycle (PubMed:17344208). a quinone + L-proline = (S)-1-pyrroline-5-carboxylate + a quinol + H(+) Binds 1 FAD per subunit. Inhibited by L-tetrahydro-2-furoic acid (THFA), L-mandelate and L-lactate (PubMed:17344208). Inhibited by N-propargylglycine (PubMed:18426222). kcat is 13 sec(-1) for L-proline. kcat is 75 sec(-1) for 3,4-dehydro-L-proline. E(0) is -75 mV. Highly thermostable. Exhibits over 85% or 60% of activity after a 1 hour or 3 hours incubation at 90 degrees Celsius, respectively. The half-life is estimated to be 257 minutes. Amino-acid degradation; L-proline degradation into L-glutamate; L-glutamate from L-proline: step 1/2. Homodimer. The measured mass is that of native enzyme without the flavin. Belongs to the proline dehydrogenase family.