Biophysical and biochemical studies of bacterial NADH:quinone oxidoreductase (NDH-1).

The mitochondrial NADH-Q oxidoreductase (Complex I) is the most complex among the major mitochondrial energy coupling enzymes. Complex I from bovine heart and Neurosporu crussu contains 41 (1) and >32 (2) distinct subunits, respectively. In contrast, bacterial NDH-1 were shown to contain only 14 subunits both in Parucoccus denilrifcans (3) and in Escherichiu coli based on their gene structure (4). Thus, the bacterial NDH-1 systems provide simpler models for studies of the Site I electron transfer and energy coupling mechanisms. Here we focus on our recent studies of the NDH-1, in situ and in vilro, of photosynthetic bacteria and of E. coli.