Open AccessDifferences in sensitivity to NADH of purified pyruvate dehydrogenase complexes of Enterococcus faecalis , Lactococcus lactis , Azotobacter vinelandii and Escherichia coli : Implications for their activity in vivo
Author(s) -
Snoep Jacky L.,
Graef Mark R.,
Westphal Adrie H.,
Kok Arie,
Joost Teixeira de Mattos M.,
Neijssel Oense M.
Publication year - 1993
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1993.tb06586.x
Subject(s) - azotobacter vinelandii , lactococcus lactis , enterococcus faecalis , escherichia coli , biochemistry , nad+ kinase , biology , microbiology and biotechnology , nitrogenase , chemostat , cofactor , pyruvate dehydrogenase complex , bacteria , chemistry , enzyme , lactic acid , nitrogen fixation , genetics , gene
The effect of NADH on the activity of the purified pyruvate dehydrogenase complexes (PDHc) of Enterococcus (Ec.) faecalis, Lactococcus lactis, Azotobacter vinelandii and Escherichia coli was determined in vitro. It was found that the PDHc of E. coli and L. lactis was active only at relatively low NADH/NAD ratios, whereas the PDHc of Ec. faecalis was inhibited only at high NADH/NAD ratios. The PDHc of Azotobacter vinelandii showed an intermediate sensitivity. The organisms were grown in chemostat culture under conditions that led to different intracellular NADH/NAD ratios and the PDHc activities in vivo could be calculated from the specific rates of product formation. Under anaerobic growth conditions, only Ec. faecelis expressed PDHc activity in vivo. The activities in vivo of the complexes of the different organisms were in good agreement with their properties determined in vitro. The physiological consequences of these results are discussed.