Table I.
Parameter | Enzyme
Activity
|
|||
---|---|---|---|---|
Coleoptiles
|
Seeds
|
|||
H+-ATPase | H+-PPase | H+-ATPase | H+-PPase | |
H+ Gradient | ||||
% | ||||
Steady state (ΔF) | 53 ± 6 (n = 6) | 46 ± 3 (n = 6) | 25 ± 2 (n = 5) | 63 ± 7 (n = 5) |
F min−1 | ||||
Initial velocity | 286 ± 10 (n = 6) | 35 ± 3.8 (n = 6) | 14 ± 1 (n = 6) | 128 ± 32 (n = 5) |
Hydrolysis | ||||
nmol mg−1min−1 | ||||
Initial velocity | 140 ± 30 (n = 3) | 57 ± 7 (n = 3) | 28 ± 8 (n = 3) | 131 ± 31 (n = 3) |
The initial rates of ATP and PPi hydrolysis and the formation of an H+ gradient were calculated from experiments like those shown in Figure 1 (hydrolysis). Initial velocities of H+-gradient formation are given in arbitrary units. Values represent the means ± se of n independent experiments.