Terrier N, Sauvage F X, Ageorges A, Romieu C
Unité de Recherche de Biochimie Métabolique et Technologie, Institut des Produits de la Vigne, INRA, Montpellier, France.
Planta. 2001 May;213(1):20-8. doi: 10.1007/s004250000472.
As in many fruits, the induction of grape berry (Vitis vinifera L.) ripening results in intense breakdown of malic acid. Using membrane fractions, we tested the hypothesis that changes in acidity resulted from malate vacuolar decompartmentation. The hydrolytic activities of the two primary vacuolar pumps inorganic pyrophosphatase (V-PPase; EC 3.6.1.1) and vacuolar ATPase (V-ATPase; EC 3.6.1.3) increased throughout development with an acceleration during ripening, as confirmed by Western blotting and analysis of transcript expression. The ratio of V-PPase activity to V-ATPase activity was always in favour of V-PPase and reached its maximum value at véraison. The rate of anion transport strongly increased during ripening. Before ripening, tonoplast passive permeability was low, but rose during ripening. Our data indicate that tonoplast leakage dramatically increased during ripening. This leakage is probably the prime cause of malate decompartmentation, amplified by the incapacity of oxidative phosphorylation to face increased energy demand.
与许多水果一样，葡萄果实（欧亚种葡萄）成熟会导致苹果酸大量分解。我们利用膜分离组分，验证了酸度变化源于苹果酸液泡区隔化的假说。两种主要的液泡泵——无机焦磷酸酶（V-PPase；EC 3.6.1.1）和液泡ATP酶（V-ATPase；EC 3.6.1.3）的水解活性在整个发育过程中均有所增加，在成熟期间加速增加，蛋白质免疫印迹和转录表达分析证实了这一点。V-PPase活性与V-ATPase活性的比值始终有利于V-PPase，并在转色期达到最大值。成熟期间阴离子转运速率大幅增加。成熟前，液泡膜的被动通透性较低，但在成熟过程中上升。我们的数据表明，成熟期间液泡膜渗漏显著增加。这种渗漏可能是苹果酸区隔化的主要原因，氧化磷酸化无法满足增加的能量需求进一步加剧了这种情况。
