| CD | circular dichroism |
| DCPIP | dichlorophenolindophenol |
| ESI-MS | electron spray ionization mass spectrometry |
| FAD | flavin adenine dinucleotide |
| FMN | flavin mononucleotide |
| GSA | glutamic semialdehyde |
| MBP | maltose-binding protein |
| ProDH | proline dehydrogenase |
| P5C | Δ1-pyrroline-5-carboxylate |
| P5CDH | Δ1-pyrroline-5-carboxylate dehydrogenase |
| PutA | proline utilization A |
| SDS-PAGE | sodium dodecyl sulfate polyacrylamide gel electrophoresis |
| Tt | Thermus thermophilus |
| EE | MBP-TtProDH with Phe10 and Leu12 replaced by Glu |
| ΔA | MBP-TtProDH lacking helix αA |
| ΔAB | MBP-TtProDH lacking helices αA and αB |
| ΔABC | MBP-TtProDH lacking helices αA, αB and αC |