Table I.

The difference in H⁺-ATPase and H⁺-PPase activities between tonoplast vesicles derived from coleoptiles and seeds

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.