Hydrogenase in N/sub 2/-fixing cyanobacteria

Journal Article · Sun Jan 15 00:00:00 EST 1978 · Arch. Biochem. Biophys.; (United States)

DOI:https://doi.org/10.1016/0003-9861(78)90158-3· OSTI ID:5504995

Tel-or, E; Luijk, L W; Packer, L

Hydrogenase has been examined in two species of aerobically grown cyanobacteria (blue-green algae), Nostoc muscorum and Anabaena cylindrica, with respect to H/sub 2/ production and consumption. These activities are found both in heterocysts and in vegetative cell preparations, but the characteristics of the enzyme in the two cell types differ. H/sub 2/ production requires an artificial electron mediator such as methylviologen, and it can be driven by artificial electron donors with and without light and by a wide variety of organic substrates for which enzymes exist for NADP and methylviologen reduction. This activity is similar in heterocysts and vegetative cells of both species and is mainly found in the soluble rather than membrane fraction. H/sub 2/ consumption, however, occurs without added mediators or acceptors at 10-fold higher rates than H/sub 2/ production and 10-fold greater activity in heterocysts. H/sub 2/ consumption activity is membrane bound, has a high affinity for H/sub 2/ (K/sub m/ = 50 ..mu..M), and is augmented by light and low concentrations of oxygen. This activity of hydrogenase is mainly found in heterocysts and is poised unidirectionally toward H/sub 2/ consumption. Since nitrogenase activity is localized in heterocysts, it suggests that H/sub 2/ leaked by nitrogenase during N/sub 2/ fixation can be recycled by hydrogenase.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 5504995
• Journal Information: Arch. Biochem. Biophys.; (United States), Vol. 185:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ALGAE
HYDROGENASE
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
ANAEROBIC CONDITIONS
CELL MEMBRANES
ENZYMES
HYDROGEN
NADP
NITROGEN FIXATION
VISIBLE RADIATION
CELL CONSTITUENTS
COENZYMES
CRYOGENIC FLUIDS
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUIDS
KINETICS
MEMBRANES
NONMETALS
NUCLEOTIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PLANTS
RADIATIONS
REACTION KINETICS
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550700 - Microbiology
550500 - Metabolism