EO9（3-羟甲基-5-环氧乙基-1-甲基-2-（H-吲哚-4,7-酮）-丙-2-烯醇）是一种新型吲哚喹啉醌，结构类似于需要还原生物活化的奎宁抗癌药物丝裂霉素C。NAD（P）H：（酮受体）氧化还原酶（酮还原酶，DT-二嗪酚蓝，EC 1.6.99.2）是一种必需的2电子供体酶，可还原各种醌类，从而产生生物活化或生物保护作用。我们利用来自大鼠Walker 256乳腺肿瘤细胞和人类HT29结肠癌细胞的酮还原酶（QR）制剂，表征了这种酶在EO9还原代谢中的作用。在最佳条件下，通过在酶、醌底物、NADH和牛血清白蛋白存在下检测550 nm处细胞色素c还原，并通过EO9吸收波长550 nm降低来确认QR活性。大鼠和人类肿瘤细胞酶都催化了基准醌类萘醌的还原，Km值相似，为1.4-3.1微米，尽管人类制剂的Vmax值要低7到8倍。大鼠Walker QR可以轻松还原EO9。平均Km值约为15微米，比萘醌高5倍，Vmax值约为2.5μmol还原一mg-1蛋白质，比萘醌低6倍。EO9也可以通过HT29人类结肠癌细胞的QR代谢，但效率比大鼠肿瘤酶低得多。例如，在校正两种制剂的特异活性差异后，在100微米的底物浓度下，速率比Walker肿瘤酶低6倍。（摘要截断至250个单词）

EO9 [3-hydroxymethyl-5-aziridinyl-1-methyl-2-(H-indole-4, 7-indione)-propenol] is a novel indoloquinone structurally related to mitomycin C, a quinone anticancer drug that requires reductive bioactivation. NAD(P)H: (quinone-acceptor) oxidoreductase (quinone reductase, DT-diaphorase, EC 1.6.99.2) is an obligate 2-electron donating enzyme that can reduce a variety of quinones resulting either in bioactivation or bioprotection. Using quinone reductase (QR) preparations from rat Walker 256 mammary tumor cells and human HT29 colon carcinoma cells, we have characterized the role of this enzyme in EO9 reductive metabolism. QR activity was assayed under optimal conditions by following cytochrome c reduction at 550 nm in the presence of enzyme, quinone substrate, NADH, and bovine albumin, and confirmed by loss of EO9 absorbance at 550 nm. Both the rat and human tumor cell enzymes catalyzed reduction of the benchmark quinone menadione with a similar Km of 1.4-3.1 microM, although the Vmax was 7 to 8-fold lower for the human preparation. EO9 was readily reduced by the rat Walker QR. The mean Km was about 5-fold higher than for menadione at around 15 microM and the Vmax was 6-fold lower at around 2.5 mumol of cytochrome c reduced mg-1 of protein. EO9 was also metabolized by QR from HT29 human colon carcinoma cells but rather less efficiently than by the rat tumor enzyme. For example, the rate was 6-fold lower than that for the Walker tumor enzyme at 100 microM substrate concentration after correcting for the 7- to 8-fold difference in specific activity for the two preparations.(ABSTRACT TRUNCATED AT 250 WORDS)