TABLE 2.

NDH-2 and pMMO activity after DPI treatment of M. capsulatus cellsa

Incubation conditionsMean sp act (nmol min−1 mg−1) ± SD (% of control)
Formate-dependent pMMONADH-dependent pMMONDH
0 μM DPI, 5 mM formate185.9 ± 8.4 (100)201.5 ± 21.9 (100)583.8 ± 84.1 (100)
50 μM DPI, 5 mM formate154.3 ± 27.1 (83)32.4 ± 3.2 (16.2)158.1 ± 48.7 (27.1)
500 μM DPI, 5 mM formate52.6 ± 18.1 (28.3)4.3 ± 1.2 (2.1)24.6 ± 6.3 (4.2)
50 μM DPI, no formate155.6 ± 12.7 (83.7)152.3 ± 11.0 (75.6)517.7 ± 34.3 (88.7)
  • a Cells were incubated for 10 min at 45°C under the conditions described and then washed three times with 50 mM PIPES (pH 7.2). A portion of each sample was saved for in vivo pMMO assays, and the remainder was lysed and the membranes were isolated and assayed for in vitro NADH-driven pMMO and NDH activities. Values reported are the mean of 8 to 14 measurements. Numbers in parentheses are the activities expressed as a percentage of that of the 0 μM DPI control.