Shimada Hideaki, Oginuma Michiko, Hara Akira, Imamura Yorishige
Faculty of Education, Kumamoto University, 2-40-1, Kurokami, Kumamoto 860-8555, Japan.
Chem Res Toxicol. 2004 Aug;17(8):1145-50. doi: 10.1021/tx0499012.
We have recently purified a tetrameric carbonyl reductase from the cytosolic fraction of pig heart (pig heart carbonyl reductase, PHCR), using 4-benzoylpyridine (4-BP) as the substrate. PHCR has the ability to catalyze efficiently the reduction of 9,10-phenanthrenequinone (PQ) contained in diesel exhaust particles (DEPs). Thus, the present study was attempted to characterize the inhibitory effect of PQ on the reduction of 4-BP and all-trans-retinal in pig heart cytosol. Of the DEP components examined, PQ was the most potent inhibitor for the reduction of 4-BP and all-trans-retinal in pig heart cytosol. PQ also inhibited competitively the 4-BP reduction. These results indicate that PQ inhibits the reduction of 4-BP and all-trans-retinal by acting PHCR present in pig heart cytosol. Furthermore, whether PQ induces the formation of superoxide anion radical was examined in pig heart cytosol. The absorbance of cytochrome c at 550 nm was increased with the time by adding PQ, and the increased absorbance was decreased in the presence of superoxide dismutase. A similar result was observed in the reaction system of recombinant PHCR. On the basis of these results, it is concluded that PQ not only inhibits the reduction of 4-BP and all-trans-retinal catalyzed by PHCR but also mediates superoxide formation through its redox cycling involved in PHCR. We propose the possibility that PQ disturbs the homeostasis of retinoid metabolism and induces oxidative stress in pig heart.
我们最近从猪心脏的胞质部分纯化了一种四聚体羰基还原酶（猪心脏羰基还原酶，PHCR），使用4-苯甲酰吡啶（4-BP）作为底物。PHCR能够高效催化柴油废气颗粒（DEP）中所含的9,10-菲醌（PQ）的还原反应。因此，本研究旨在表征PQ对猪心脏胞质溶胶中4-BP和全反式视黄醛还原反应的抑制作用。在所检测的DEP成分中，PQ是猪心脏胞质溶胶中4-BP和全反式视黄醛还原反应的最有效抑制剂。PQ还竞争性抑制4-BP的还原反应。这些结果表明，PQ通过作用于猪心脏胞质溶胶中存在的PHCR来抑制4-BP和全反式视黄醛的还原反应。此外，还在猪心脏胞质溶胶中检测了PQ是否诱导超氧阴离子自由基的形成。通过添加PQ，细胞色素c在550 nm处的吸光度随时间增加，而在超氧化物歧化酶存在下，增加的吸光度降低。在重组PHCR的反应体系中也观察到了类似的结果。基于这些结果，可以得出结论，PQ不仅抑制PHCR催化的4-BP和全反式视黄醛的还原反应，还通过参与PHCR的氧化还原循环介导超氧化物的形成。我们提出了PQ可能扰乱猪心脏中类视黄醇代谢的稳态并诱导氧化应激的可能性。
