Citrate substitutes for homocitrate in nitrogenase of a nifV mutant of Klebsiella pneumoniae.
An organic acid extracted from purified dinitrogenase isolated from a nifV mutant of Klebsiella pneumoniae has been identified as citric acid. H2 evolution by the citrate-containing dinitrogenase is partially inhibited by CO, and by some substrates for nitrogenase. The response of maximum velocities to changes in pH for both the wild-type and the NifV- dinitrogenase was compared. No substantial differences between the enzymes were observed, but there are minor differences. Both enzymes are stable in the pH range 4.8-10, but the enzyme activities dropped dramatically below pH 6.2.
Liang
J
J
Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706.
Madden
M
M
Shah
V K
VK
Burris
R H
RH
D002951:Citrates / Q000378:metabolism*; D019343:Citric Acid; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics*; D008983:Molybdoferredoxin / Q000378:metabolism*; D009586:Nitrogen Fixation / Q000235:genetics*; D009591:Nitrogenase / Q000235:genetics* / Q000378:metabolism; D014233:Tricarboxylic Acids / Q000378:metabolism*
D002951:Citrates; D008983:Molybdoferredoxin; D014233:Tricarboxylic Acids; D019343:Citric Acid; C028143:homocitric acid; D009591:Nitrogenase