Costa A D, Nantes I L, Jezek P, Leite A, Arruda P, Vercesi A E
Departamento de Patologia Clínica (NMCE), Faculdade de Ciências Médicas, Universidade Estadual de Campinas, SP, Brazil.
J Bioenerg Biomembr. 1999 Oct;31(5):527-33. doi: 10.1023/a:1005408809619.
In the present study we have observed a higher state of coupling in respiring mitochondria isolated from green as compared to red tomatoes (Lycopersicon esculentum, Mill.). Green tomato mitochondria produced a membrane potential (deltapsi) high enough to phosphorylate ADP, whereas in red tomato mitochondria, BSA and ATP were required to restore deltapsi to the level of that obtained with green tomato mitochondria. This supports the notion that such uncoupling in red tomato mitochondria is mediated by a plant uncoupling mitochondrial protein (PUMP; cf. Vercesi et al., 1995). Nevertheless, mitochondria from both green and red tomatoes exhibited an ATP-sensitive linoleic acid (LA)-induced deltapsi decrease providing evidence that PUMP is also present in green tomatoes. Indeed, proteoliposomes containing reconstituted green or red tomato PUMP showed LA uniport and LA-induced H+ transport. It is suggested that the higher concentration of free fatty acids (PUMP substrates) in red tomatoes could explain the lower coupling state in mitochondria isolated from these fruits.
在本研究中，我们观察到，与红色番茄（番茄，Mill.）相比，从绿色番茄中分离出的呼吸线粒体具有更高的偶联状态。绿色番茄线粒体产生的膜电位（Δψ）足以使ADP磷酸化，而在红色番茄线粒体中，需要牛血清白蛋白（BSA）和ATP才能将Δψ恢复到绿色番茄线粒体所达到的水平。这支持了红色番茄线粒体中的这种解偶联是由植物解偶联线粒体蛋白（PUMP；参见Vercesi等人，1995年）介导的这一观点。然而，绿色和红色番茄的线粒体均表现出对ATP敏感的亚油酸（LA）诱导的Δψ降低，这证明绿色番茄中也存在PUMP。实际上，含有重组绿色或红色番茄PUMP的蛋白脂质体显示出LA单向转运和LA诱导的H⁺转运。有人认为，红色番茄中游离脂肪酸（PUMP底物）的浓度较高，可以解释从这些果实中分离出的线粒体中较低的偶联状态。
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