Botany School, University of Cambridge, Downing Street, CB2 3EA, Cambridge, UK.
Planta. 1981 Oct;153(2):140-9. doi: 10.1007/BF00384095.
Ion stimulation and some other properties of an ATPase activity associated with vacuoles isolated from storage roots of red beet (Beta vulgaris L.) have been determined. The ATPase had a specific requirement for Mg(2+) and in the presence of Mg(2+) it was stimulated by salts of monovalent cations. The degree of stimulation by monovalent salts was influenced mainly by the anion and the order of effectiveness of the anions tested was Cl(-)>HCO 3 (-) >Br(-)>malate>acetate>SO 4 (2-) . For any given series of anions the magnitude of the stimulation obtained was influenced by the accompanying cation (NH 4 (+) ≫ Na(+)>K(+)). This cation effect was abolished by 0.01% (v/v) Triton X-100 and it is suggested that it is the result of different permeabilities of membrane vesicles to the cations. There was no evidence of synergistic stimulation of the ATPase by mixtures of Na(+) and K(+). KCl- and NaCl-stimulation was maximal with salt concentrations in the range 60-150 mM. The true substrate of the enzyme was shown to be MgATP. It was shown that KCl stimulation was the result of an increase in Vmax rather than a change in the affinity of the enzyme for MgATP. The ATPase was inhibited by N,N'-dicyclohexylcarbodiimide, diethylstilbestrol, mersalyl and KNO3 but other inhibitors tested (azide, oligomycin, orthovanadate, K3[Cr(oxalate)6] and ethyl-3-[3-dimethylaminopropyl]carbodiimide) were without effect or caused only partial inhibition at the highest concentration tested. The ATPase activity was equally distributed between pellet and supernatant fractions obtained after the subfractionation of vacuoles but the properties of the ATPase in each fraction were the same. It is suggested that beet vacuoles possess only one ATPase. The properties of the ATPase are compared with those of ATPases associated with other plant membranes and organelles and its possible role in transport at the tonoplast is discussed.
已测定与红甜菜（Beta vulgaris L.）贮藏根分离的液泡相关的 ATP 酶的离子刺激和其他一些性质。该 ATP 酶对 Mg（2+）有特定的要求，并且在存在 Mg（2+）的情况下，它被单价阳离子盐刺激。单价盐的刺激程度主要受阴离子影响，所测试的阴离子的有效顺序为 Cl（-）> HCO 3（-）> Br（-）> 苹果酸盐> 醋酸盐> SO 4（2-）。对于任何给定的阴离子系列，所获得的刺激程度都受到伴随阳离子的影响（NH 4（+）> Na（+）> K（+））。该阳离子效应被 0.01%（v/v）Triton X-100 消除，并且认为它是膜囊泡对阳离子不同通透性的结果。没有证据表明 Na（+）和 K（+）混合物对 ATP 酶有协同刺激作用。KCl-和 NaCl-刺激作用在盐浓度为 60-150mM 范围内达到最大。该酶的真正底物被证明是 MgATP。结果表明，KCl 刺激是由于 Vmax 增加而不是酶对 MgATP 亲和力的变化所致。ATP 酶被 N，N'-二环己基碳二亚胺、己烯雌酚、mersalyl 和 KNO3 抑制，但其他测试的抑制剂（叠氮化物、寡霉素、正钒酸盐、K3[Cr（草酸盐）6]和乙基-3-[3-二甲基氨基丙基]碳二亚胺）没有作用或仅在最高测试浓度下引起部分抑制。ATP 酶活性均匀分布于液泡亚分级分离后获得的沉淀和上清部分之间，但每个部分中的 ATP 酶性质相同。表明甜菜液泡仅具有一种 ATP 酶。将 ATP 酶的性质与其他植物膜和细胞器相关的 ATP 酶的性质进行比较，并讨论其在质膜中的运输作用。
