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. Author manuscript; available in PMC: 2020 Apr 28.
Published in final edited form as: Biochim Biophys Acta Bioenerg. 2017 Sep 29;1859(1):8–18. doi: 10.1016/j.bbabio.2017.09.006

Table 3.

H2-driven NAD+ reduction activity of the HtSH proteina in the presence of various O2 concentrations.

O2 / H2 / N2 fractionsb (% v/v) [O2] (μM) Hydrogenase activity in the presence of O2 (U mg−1 of protein)c kcat (s−1) Hydrogenase activity (%)
0 / 33.33 / 66.66 0.00 16 ± 2 45.9 100
0.2 / 33.33 / 66.46 1,9 15 ± 4 43.0 94.2
2 / 33.33 / 64.66 18,8 7.7 ± 0.3 21.5 49.8
10 / 33.33 / 56.66 94,0 1.3 ± 0.5 3.6 16.6
a

HtSH was purified by affinity chromatography as described in materials and methods.

b

For each O2 concentration, a fixed volume of H2-saturated buffer was mixed with various proportions of O2- and N2-saturated buffers. The gas phase contained the corresponding gas mixtures.

c

H2-mediated NAD+ reduction activity was measured at 50 °C and pH 6.5.