Characterization of the East Asian variant of aldehyde dehydrogenase-2: bioactivation of nitroglycerin and effects of Alda-1.
Characterization of the East Asian variant of aldehyde dehydrogenase-2: bioactivation of nitroglycerin and effects of Alda-1.
复制标题
DOI：
10.1074/jbc.m109.014548
复制
发表时间：
2010-01-08
期刊：
影响因子：
--
通讯作者：
Mayer B
中科院分区：
文献类型：
--
作者：
Beretta M;Gorren AC;Wenzl MV;Weis R;Russwurm M;Koesling D;Schmidt K;Mayer B
线粒体醛脱氢酶 (ALDH2) 的东亚变体表现出脱氢酶、酯酶和硝酸甘油 (GTN) 脱硝活性显着降低。据报道，小分子 Alda-1 可以部分恢复该变体的低乙醛脱氢酶活性。在本研究中，我们比较了野生型酶 (ALDH2*1) 与亚洲变体酶 (ALDH2*2) 的 GTN 生物活性和 Alda-1 的影响。 Alda-1 使 ALDH2*1 和 ALDH2*2 的乙醛氧化分别增加约 1.5 倍和 6 倍，并刺激两种酶的酯酶活性，其程度与辅酶 NAD 相似。 NAD 的作用是双相的，在 ≥5 mm 处发生明显的抑制。在 1 mm NAD 存在下，Alda-1 刺激 ALDH2*2 催化的酯水解 73 倍，而 NAD 刺激的 ALDH2*1 活性受到抑制，因为在药物存在下，NAD 的抑制效力增加了 20 倍。尽管 ALDH2*2 的 GTN 脱硝活性和 GTN 亲和力比 ALDH2*1 低 7 倍，但一氧化氮形成速率仅降低 2 倍，并且在饱和 GTN 时，可溶性鸟苷酸环化酶 (sGC) 激活比野生型 ALDH2 更明显。 Alda-1 会轻微抑制 GTN 脱硝，并且在任一变体存在的情况下都不会增加 GTN 诱导的 sGC 激活。目前的结果表明，Alda-1 通过改善 NAD 结合来刺激已建立的 ALDH2 活性，但不会改善亚洲变体的 GTN 结合亲和力。此外，我们的数据揭示了 GTN 还原酶活性和 sGC 激活之间的意外差异，表明 GTN 脱硝和生物激活可能反映了 ALDH2 催化 GTN 生物转化的独立途径。
The East Asian variant of mitochondrial aldehyde dehydrogenase (ALDH2) exhibits significantly reduced dehydrogenase, esterase, and nitroglycerin (GTN) denitrating activities. The small molecule Alda-1 was reported to partly restore low acetaldehyde dehydrogenase activity of this variant. In the present study we compared the wild type enzyme (ALDH2*1) with the Asian variant (ALDH2*2) regarding GTN bioactivation and the effects of Alda-1. Alda-1 increased acetaldehyde oxidation by ALDH2*1 and ALDH2*2 approximately 1.5- and 6-fold, respectively, and stimulated the esterase activities of both enzymes to similar extent as the coenzyme NAD. The effect of NAD was biphasic with pronounced inhibition occurring at ≥5 mm. In the presence of 1 mm NAD, Alda-1 stimulated ALDH2*2-catalyzed ester hydrolysis 73-fold, whereas the NAD-stimulated activity of ALDH2*1 was inhibited because of 20-fold increased inhibitory potency of NAD in the presence of the drug. Although ALDH2*2 exhibited 7-fold lower GTN denitrating activity and GTN affinity than ALDH2*1, the rate of nitric oxide formation was only reduced 2-fold, and soluble guanylate cyclase (sGC) activation was more pronounced than with wild type ALDH2 at saturating GTN. Alda-1 caused slight inhibition of GTN denitration and did not increase GTN-induced sGC activation in the presence of either variant. The present results indicate that Alda-1 stimulates established ALDH2 activities by improving NAD binding but does not improve the GTN binding affinity of the Asian variant. In addition, our data revealed an unexpected discrepancy between GTN reductase activity and sGC activation, suggesting that GTN denitration and bioactivation may reflect independent pathways of ALDH2-catalyzed GTN biotransformation.