Abstract
Publisher Summary The chapter focuses on the work done toward this aspect; toward understanding how respiration and nitrogen fixation can function simultaneously in Azotobacter. Accordingly, only those aspects of this subject that are connected with the physiology of nitrogen fixation in aerobes will be discussed. In particular, determination of the constitution and behavior of this organism's branched respiratory chain has contributed to the understanding of how respiration controls nitrogen fixation. All nitrogenases from both aerobic and anaerobic organisms comprise two non-haem iron proteins, which have the same requirements for enzymic activity in vitro— namely, an anaerobic environment, a source of ATP, and a reluctant. The two component proteins that make up the nitrogenase enzyme complement each other in cross reactions between nitrogenase fractions from aerobic and some anaerobic sources and physiological electron carriers from one class of bacteria can donate electrons to nitrogenase from the other. The absence of oxygen is mandatory in nearly all measurements of nitrogen fixation in vitro. Crude preparations that show nitrogenase activity in the presence of oxygen have been obtained from aerobic nitrogen fixers. From the foregoing evidence it is reasonable to assume that nitrogen fixation is an anaerobic process catalyzed by oxygen-sensitive proteins. How these operate and survive in an aerobic bacterium is discussed in detail. Because oxygen uptake is the major electron-utilizing metabolic process in Azotobacter, the respiratory chain involving electron transport and oxidative phosphorylation are described.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call