CHARACTERIZATION OF A MTROGENASE-LIKE ENZYME CATALYZING PROTOCHLOROPHYLLIDE REDUCTION FROM RHQDOBACTER CAPSULATUS

摘要

Protochlorophyllide (Pchlide) is an important intermediate in the biosynthesis of chlorophylls (Chls) and bacteriochlorophylls (BChls). Two different enzymes in photosynthetic organisms are capable of reducing a double bond in D-ring of Pchlide in a stereo-specific manner to form chlorophyllide (Chlide). One enzyme is the light-dependent Pchlide oxidoreductase (LPOR) and the other is darkoperative Pchlide oxidoreductase (DPOR), which is the determinant enzyme for these photosynthetic organisms to synthesize (B)Chls in the dark (Fujita & Bauer 2003). In our previous work, we demonstrated that DPOR consists of two separable components, L-protein (BchL) and NB-protein (BchN-BchB), with nitrogenase-like features (Fujita & Bauer 2000). Biochemical properties of each component are, however, still largely unknown.