TY - JOUR
T1 - Hydrogenase in N2-fixing cyanobacteria
AU - Tel-Or, Elisha
AU - Luijk, Leonard W.
AU - Packer, Lester
PY - 1978/1/15
Y1 - 1978/1/15
N2 - Hydrogenase has been examined in two species of aerobically grown cyanobacteria (blue-green algae), Nostoc muscorum and Anabaena cylindrica, with respect to H2 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. H2 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. H2 consumption, however, occurs without added mediators or acceptors at 10-fold higher rates than H2 production and 10-fold greater activity in heterocysts. H2 consumption activity is membrane bound, has a high affinity for H2 (Km = 50 μM), and is augmented by light and low concentrations of oxygen. This activity of hydrogenase is mainly found in heterocysts and is poised unidirectionally toward H2 consumption. Since nitrogenase activity is localized in heterocysts, it suggests that H2 leaked by nitrogenase during N2 fixation can be recycled by hydrogenase.
AB - Hydrogenase has been examined in two species of aerobically grown cyanobacteria (blue-green algae), Nostoc muscorum and Anabaena cylindrica, with respect to H2 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. H2 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. H2 consumption, however, occurs without added mediators or acceptors at 10-fold higher rates than H2 production and 10-fold greater activity in heterocysts. H2 consumption activity is membrane bound, has a high affinity for H2 (Km = 50 μM), and is augmented by light and low concentrations of oxygen. This activity of hydrogenase is mainly found in heterocysts and is poised unidirectionally toward H2 consumption. Since nitrogenase activity is localized in heterocysts, it suggests that H2 leaked by nitrogenase during N2 fixation can be recycled by hydrogenase.
UR - https://www.scopus.com/pages/publications/0017904738
U2 - 10.1016/0003-9861(78)90158-3
DO - 10.1016/0003-9861(78)90158-3
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
C2 - 23725
AN - SCOPUS:0017904738
SN - 0003-9861
VL - 185
SP - 185
EP - 194
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -