期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1971
卷号：68
期号：9
页码：2016-2018
DOI：10.1073/pnas.68.9.2016
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Purified cell-free extracts of Klebsiella pneumoniae reduce N2, N3-, CN-, or C2H2 in the absence of an ATP-generating system when substrate concentrations of ATP are used. The optimum Mg++/ATP ratio is 0.5. Michaelis constants for the reduction of substrates calculated from kinetic studies of K. pneumoniae nitrogenase were similar to those that have been reported for Azotobacter vinelandii and Clostridium pasteurianum. Hill plots of the kinetic data are consistent with the view that there is a single binding site for each of the substrates N2, C2H2, CN-, N3-, and ATP. Inhibition studies of K. pneumoniae nitrogenase indicate that ADP competitively inhibits C2H2 reduction. Also, the reducible substrates, N3- and CN-, inhibit C2H2 reduction. The inhibition by azide is noncompetitive, that by cyanide is mixed.
