Nitrogenase Activity and Membrane Electrogenesis in the Cyanobacterium Anabaena variabilis Kütz

Publisher Website
Google Scholar
Abstract
Relationships between nitrogenase activity and individual components of the proton electrochemical potential gradient (.DELTA.~.mu.H+) in A. variabilis were investigated. The ionophore nigericin collapsed .DELTA.pH in favor of the membrane potential .DELTA..psi.; hyperpolarization of .DELTA..psi. was correlated with an increase in nitrogenase activity. A positive relationship between nitrogenase activity and membrane potential was observed using the ionophore valinomycin and the uncoupler carbonylcyanide m-chlorophenylhydrazone. Using the energy transfer inhibitor N,N''-dicyclohexylcarbodiimide, nitrogenase activity appeared to be limited by the supply of reductant rather than ATP. For intact filaments and isolated heterocysts, .DELTA..psi. may be important in regulating nitrogenase activity in vivo.