Hellström-Lindahl E, Weiner H
Biochem Pharmacol. 1985 May 1;34(9):1529-35. doi: 10.1016/0006-2952(85)90695-1.
The in vitro oxidation of benzaldehyde and acetaldehyde was studied in liver samples from disulfiram-treated and control rats. With 25 microM substrate, both cytosol and mitochondria appeared to make a nearly equal contribution to the oxidation of benzaldehyde, whereas ca. 90% of acetaldehyde oxidation occurred in mitochondria. When the Km values for benzaldehyde with aldehyde dehydrogenase (ALDH) were determined, two Km values (3 and 120 microM) were obtained with mitochondria, but only a single Km value (25 microM) was obtained with the cytosolic fraction. The relatively high Km (2.9 mM) found with microsomes makes it unlikely that microsomes are important in the oxidation of benzaldehyde. In intact mitochondria, with 200 microM acetaldehyde or benzaldehyde the matrix space enzyme accounted for 77 and 62%, respectively, of the total ALDH activity. When the activity was determined in a mixture containing both substrates, the activity was found not to be additive, indicating that both substrates are oxidized by the same matrix space enzyme. With subcellular fractions, from livers of disulfiram-treated and control rats, a greater degree of inhibition of ALDH was obtained when acetaldehyde was a substrate compared to that with benzaldehyde in cytosol and mitochondria. Microsomal ALDH was not inhibited by disulfiram. In liver slices from rats given disulfiram, a statistically significant inhibition was found when either 25 or 250 microM acetaldehyde was used (46 and 33%). With benzaldehyde, a significant inhibition (24%) was observed only with the lower substrate concentration. Finding that both mitochondrial fractions and slices were less inhibited at the higher substrate concentration implies that the high Km enzyme is not inhibited. It can be concluded that, in rat, disulfiram inhibiting liver ALDH not only affects oxidation of acetaldehyde, but also that of benzaldehyde.
在双硫仑处理的大鼠和对照大鼠的肝脏样本中研究了苯甲醛和乙醛的体外氧化。以25微摩尔底物浓度时，胞浆和线粒体对苯甲醛氧化的贡献似乎几乎相等，而约90%的乙醛氧化发生在线粒体中。当测定醛脱氢酶（ALDH）对苯甲醛的Km值时，线粒体得到两个Km值（3和120微摩尔），但胞浆部分仅得到一个Km值（25微摩尔）。微粒体中相对较高的Km值（2.9毫摩尔）表明微粒体在苯甲醛氧化中不太重要。在完整的线粒体中，以200微摩尔乙醛或苯甲醛时，基质空间酶分别占总ALDH活性的77%和62%。当在含有两种底物的混合物中测定活性时，发现活性不是相加的，这表明两种底物由相同的基质空间酶氧化。对于双硫仑处理的大鼠和对照大鼠肝脏的亚细胞部分，当乙醛作为底物时，与胞浆和线粒体中的苯甲醛相比，ALDH受到的抑制程度更大。微粒体ALDH不受双硫仑抑制。在给予双硫仑的大鼠肝脏切片中，当使用25或250微摩尔乙醛时发现有统计学意义的抑制（分别为46%和33%）。对于苯甲醛，仅在较低底物浓度下观察到显著抑制（24%）。发现在较高底物浓度下线粒体部分和切片受到的抑制较小，这意味着高Km酶未受抑制。可以得出结论，在大鼠中，双硫仑抑制肝脏ALDH不仅影响乙醛的氧化，也影响苯甲醛的氧化。
