Characteristics of the nitrogenase system of the blue-green alga Anabaena cylindrica

✍ Scribed by Haystead, A. ;Stewart, W. D. P.

• Publisher: Springer-Verlag
• Year: 1972
• Weight: 665 KB
• Volume: 82
• Category: Article
• ISSN: 0003-9276
• DOI: 10.1007/bf00424936

✦ Synopsis

The requirements for activity of blue-green algal nitrogenase have been studied. The optimal concentration ranges for ATP and Na~S204 are 2--3 m~ and 4--10 mlYl respectively. A magnesium requirement has been confirmed but the enzyme is not specific for Mg ~+, Co 2+ and Mn 2+ will also support activity but Ca ~+, Cu 2+ and Zn 2+ will not. The partially purified enzyme is soluble and specific activities of 50--100 nmoles C2H4/mg protein/rain have been obtained. The biochemical characteristics of the enzyme, as determined in studies using enzyme inhibitors, are similar to those of bacterial and legume nitrogenases in that the enzyme is a metallo-protein containing iron and reduced thiol groups and the redox capacity of the enzyme involves a possible valency change in the iron. The transfer of electrons from H~ via a bacterial hydrogenase has been shown to be mediated, at least in part, by ferredoxin. The role of ferredoxin and the interrelationships between photosynthesis, reduetant pool and hydrogen metabolism are discussed in the light of recent results obtained by ourselves and other workers.