This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Houchins, J. P. Articles by Burris, R. H. Search for Related Content PubMed PubMed Citation Articles by Houchins, J. P. Articles by Burris, R. H. Agricola Articles by Houchins, J. P. Articles by Burris, R. H.

Articles

Physiological Reactions of the Reversible Hydrogenase from Anabaena 7120 ¹

Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706

The reversible hydrogenase from Anabaena 7120 appeared when O₂ was continuously removed from a growing culture. Activity increased further when cells were incubated under argon in the dark or in the light plus 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Hydrogenase existed in an inactive state during periods of O₂ evolution. It could be reductively activated by exposure to reduced methyl viologen or by dark, anaerobic incubation. Hydrogenase-containing cells evolved H₂ slowly during dark anaerobic incubations, and the rate of H₂ evolution was increased by illumination with low intensity light. Light enhancement of H₂ evolution was of short duration and was eliminated by the ferredoxin antagonist disalicylidene diaminopropane. Physiological acceptors that supported H₂ uptake included NO₃^–, NO₂^–, and HSO₃^–, and light had a slight influence on the rate of H₂ uptake with these acceptors. Low levels of O₂ supported H₂ uptake, but higher concentrations of O₂ inactivated the hydrogenase. Hydrogen uptake with HCO₃^– as acceptor was the most rapid reaction measured, and it was strictly light-dependent. It occurred only at low light intensities, and higher light intensities restored normal O₂-evolving photosynthesis. It is suggested that hydrogenase is present to capture exogenous H₂ as a source of reducing equivalents during growth in anaerobic environments.

¹ Supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison, by National Science Foundation grant PCM77-21038, and by Public Health Service grant AI-00848 from the National Institute of Allergy and Infectious Diseases.