Beliaeva T N, Faddeeva M D
Tsitologiia. 1995;37(3):237-48.
Processes of energy transduction were studied in isolated rat liver mitochondria, taken as a possible target for DNA intercalators, which differs from a usual one, associated with nucleic acid metabolism reactions. In the mitochondrial suspension, changes in respiration rates and latent ATPase activity in controlled state were defined in addition to a decrease in respiratory control index (V2/V1) and P/O ratio under the influence of DNA intercalators, benzophenanthridine alkaloid sanguinarine and acridine derivative APhMA. Within the range of examined sanguinarine and APhMA concentrations, the increase in respiration rate and activation of latent ATPase activity of mitochondrial suspension was first determined, with the maxima of these activities at 10(-4) M for both the agents. A further increase in sanguinarine and APhMA concentrations caused the inhibition of these reactions. Such dose-dependent shapes, with a maximum for the curves of mitochondrial respiration rate and ATPase activity "bell-shaped"), are typical for the majority of so far known uncouplers of oxidative phosphorylation in mitochondria. The fall of V2/V1 and P/O, under the influence of sanguinarine and APhMA, evidenced for the inhibition of ATP synthesis in mitochondria. The mechanism of uncoupling by sanguinarine and APhMA was supposed to differ from that by protonophores. It has been suggested that the uncoupling of oxidative phosphorylation by sanguinarine and APhMA was associated with the ability of these organic cations to neutralize negative charges near the external side of energized internal mitochondrial membranes. Correlation between the capacity for DNA intercalation and that for the energy transfer inhibition in mitochondria of these two agents is presumably based on the importance of positive charges and hydrophobic interactions, both for intercalation into polynucleotide double helices and for negative charges neutralization in energized mitochondrial membranes. Among DNA intercalators, so far examined, no agent has been established, which would not disturb the coupling of respiration and phosphorylation in mitochondria. However, there is no strong correlation for the agents between the ability to intercalate into DNA double helix and to disturb the energy transfer processes in mitochondria. Sanguinarine, which is more potent, as a DNA intercalator, than APhMA, is weaker than APhMA as an uncoupler of mitochondrial oxidative phosphorylation. For DNA-intercalation, the steric conformity between sizes of the intercalator molecule and of DNA base pairs is of great importance. On the other hand, for mitochondrial energy transfer disturbance, the agent ability to achieve sites of negative charges in the energized inner membranes is more significant.
以分离的大鼠肝线粒体作为DNA嵌入剂的可能作用靶点，研究了能量转导过程。该靶点不同于与核酸代谢反应相关的常见靶点。在线粒体悬浮液中，除了在DNA嵌入剂、二苯菲啶生物碱血根碱和吖啶衍生物APhMA的影响下呼吸控制指数（V2/V1）和P/O比值降低外，还确定了受控状态下呼吸速率和潜在ATP酶活性的变化。在检测的血根碱和APhMA浓度范围内，首先确定了线粒体悬浮液呼吸速率的增加和潜在ATP酶活性的激活，两种试剂在10^(-4) M时这些活性达到最大值。血根碱和APhMA浓度的进一步增加导致这些反应受到抑制。这种剂量依赖性的形状，线粒体呼吸速率和ATP酶活性曲线呈“钟形”最大值，是大多数目前已知的线粒体氧化磷酸化解偶联剂的典型特征。在血根碱和APhMA的影响下，V2/V1和P/O的下降证明了线粒体中ATP合成受到抑制。推测血根碱和APhMA的解偶联机制不同于质子载体的解偶联机制。有人提出，血根碱和APhMA引起的氧化磷酸化解偶联与这些有机阳离子中和线粒体内膜外侧附近负电荷的能力有关。这两种试剂的DNA嵌入能力与线粒体能量传递抑制能力之间的相关性可能基于正电荷和疏水相互作用的重要性，这两者对于插入多核苷酸双螺旋以及中和线粒体膜外侧的负电荷都很重要。在目前检测的DNA嵌入剂中，尚未发现不会干扰线粒体呼吸与磷酸化偶联的试剂。然而，对于这些试剂来说，插入DNA双螺旋的能力与干扰线粒体能量传递过程的能力之间没有很强的相关性。作为DNA嵌入剂比APhMA更有效的血根碱，作为线粒体氧化磷酸化解偶联剂比APhMA弱。对于DNA嵌入，嵌入剂分子大小与DNA碱基对大小之间的空间适配性非常重要。另一方面，对于线粒体能量传递干扰，试剂到达内膜外侧负电荷位点的能力更为重要。
