Rugolo M, Antognoni F, Flamigni A, Zannoni D
Department of Biology, Biochemistry Laboratory, University of Bologna, I-40126 Bologna, Italy.
Plant Physiol. 1991 Jan;95(1):157-63. doi: 10.1104/pp.95.1.157.
The effect of polyamines (putrescine, spermine, and spermidine) on the oxidation of exogenous NADH by Jerusalem artichoke (Helianthus tuberosus L. cv. OB1) mitochondria, have been studied. Addition of spermine and/or spermidine to a suspension of mitochondria in a low-cation medium (2 millimolar-K(+)) caused a decrease in the apparent K(m) and an increase in the apparent V(max) for the oxidation of exogenous NADH. These polycations released by screening effect the mitochondrially induced quenching of 9-aminoacridine fluorescence, their efficiency being dependent on the valency of the cation (C(4+) > C(3+)). Conversely, putrescine only slightly affected both kinetic parameters of exogenous NADH oxidation and the number of fixed charges on the membranes. Spermine and spermidine, but not putrescine, decreased the apparent K(m) for Ca(2+) from about 1 to about 0.2 micromolar, required to activate external NADH oxidation in a high-cation medium, containing physiological concentrations of Pi, Mg(2+) and K(+). The results are interpreted as evidence for a role of spermine and spermidine in the modulation of exogenous NADH oxidation by plant mitochondria in vivo.
研究了多胺（腐胺、精胺和亚精胺）对菊芋（Helianthus tuberosus L. cv. OB1）线粒体氧化外源NADH的影响。在低阳离子培养基（2毫摩尔-K(+)）中，向线粒体悬浮液中添加精胺和/或亚精胺会导致外源NADH氧化的表观K(m)降低，表观V(max)增加。这些聚阳离子通过屏蔽效应释放线粒体诱导的9-氨基吖啶荧光猝灭，其效率取决于阳离子的价态（C(4+) > C(3+)）。相反，腐胺对外源NADH氧化的动力学参数和膜上固定电荷数量仅有轻微影响。在含有生理浓度的Pi、Mg(2+)和K(+)的高阳离子培养基中，精胺和亚精胺而非腐胺可将激活外源NADH氧化所需的Ca(2+)表观K(m)从约1微摩尔降至约0.2微摩尔。这些结果被解释为精胺和亚精胺在体内调节植物线粒体氧化外源NADH中起作用的证据。
