Oxygen gradients in mitochondria examined with delayed luminescence from excited-state triplet probes.
Oxygen gradients in mitochondria examined with delayed luminescence from excited-state triplet probes.
复制标题
使用激发态三重态探针的延迟发光检查线粒体中的氧梯度。
作者：
J. Vanderkooi;W. W. Wright;M. Erecínska
描述了可被分子氧猝灭并分配到膜中的磷酸化探针。这些探针是卟啉的衍生物，其中中心金属锌或钯诱导系统间交叉以提高三重态产率。探针在膜悬浮液中的位置取决于卟啉上侧基的电荷分布。在卵磷脂人工膜中，分配到膜中的探针对相变敏感。在线粒体中，这些膜探针在膜蛋白中的转移距离内。虽然膜中的氧的绝对浓度不能通过这种方法来确定，通过比较在积极呼吸和抑制条件下的膜相的探针在水相中的氧依赖性，它是可能的检查线粒体表面的O2耗尽的程度。我们表明，在氧张力为0.2 μ M和更高，这些梯度是微不足道的，在通常的线粒体耗氧率。
Phosphorescent probes are described that are quenchable by dioxygen and that partition into membranes. These probes are derivatives of porphyrin, in which the central metal, either zinc or palladium, induces intersystem crossing to enhance the triplet yield. The location of the probe in a suspension of membranes depends upon the charge distribution of side groups on the porphyrins. Probes that partition into the membrane are sensitive to phase transitions in lecithin artificial membranes. In the mitochondria these membrane probes are within transfer distance from tryptophans in membrane proteins. Although absolute concentrations of oxygen in membranes cannot be determined by this method, by comparing the oxygen dependence of a probe in the aqueous phase with that in the membrane phase under actively respiring and inhibited conditions, it is possible to examine the extent of O2 depletion at the mitochondrial surface. We show that at oxygen tensions of 0.2 microM and higher these gradients are insignificant at usual oxygen consumption rates of mitochondria.