Enzymatic requirement for cyanamide inactivation of rat liver aldehyde dehydrogenase.
Enzymatic requirement for cyanamide inactivation of rat liver aldehyde dehydrogenase.
复制标题
氰胺灭活大鼠肝醛脱氢酶的酶促需求。
DOI：
10.1016/0006-2952(85)90495-2
复制
发表时间：
1985
影响因子：
5.8
通讯作者：
Weiner,H
中科院分区：
文献类型：
--
作者：
Svanas,GW;Weiner,H
在大鼠肝切片、完整线粒体和不同纯度的肝组织中，用氨腈体外灭活乙醛脱氢酶（ALDH）。低KmALDH比高Kmform更容易受到氰胺灭活。此外，NAD或NADH的存在是氨腈抑制ALDH活性所必需的。低浓度的氰胺需要酶促转化为可抑制LDH的活性衍生物。本研究中的数据与DeMasteret等人[Biochem.biophys. Res. Commun.，122，358（1984）]，过氧化氢酶是氰酰胺转化酶。过氧化氢酶活性的抑制剂，丙二酸，降低了在完整的线粒体中的ALDH的氰胺失活率。此外，亲和层析纯化的ALDH，无过氧化氢酶活性，不能被氰胺灭活。这种亲和纯化的ALDH仅被高浓度的氨腈灭活。因此，可能存在ALDH失活的替代途径，其中不需要氨腈的酶促修饰。然而，ALDH制剂中的污染酶可能能够活化氰胺。
Thein vitroinactivation of aldehyde dehydrogenase (ALDH) by cyanamide in rat liver slices, in intact mitochondria, and at various stages of purity was characterized. Low-KmALDH was more susceptible to cyanamide inactivation than was the high-Kmform. In addition, the presence of NAD or NADH was necessary for cyanamide inhibition of the ALDH activity. Cyanamide at low concentrations required enzymatic conversion to a reactive derivative that could inhibitioLDH. The data in this study are consistent with the suggestion of DeMasteret al. [Biochem. biophys. Res. Commun.,122, 358 (1984)] that catalase is the cyanamide-converting enzyme. An inhibitor of catalase activity, malonate, decreased the rate of cyanamide inactivation of ALDH in intact mitochondria. Furthermore, affinity chromatography-purified ALDH, free of catalase activity, was not susceptibie tomcyanamide inactivation. This affinity-purified ALDH was only inactivated by high concentrations of cyanamide. Thus, an alternative pathway for ALDH inactivation may exist in which enzymatic modification of cyanamide is not necessary. It is likely, however, that a contaminating enzyme in the ALDH preparation is capable of activating cyanamide.