Spector T, Harrington J A, Porter D J
Wellcome Research Laboratories, Research Triangle Park, NC 27709.
Biochem Pharmacol. 1991 Jun 21;42(1):91-6. doi: 10.1016/0006-2952(91)90685-x.
The mode of inactivation of herpes simplex virus type 1 and human ribonucleotide reductases by 2-acetylpyridine 5-[(2-chloroanilino)-thiocarbonyl]-thiocarbonohydrazone++ + (348U87) was determined and compared to that described previously [Porter et al. Biochem Pharmacol 39: 639-646, 1990] for 2-acetylpyridine 5-[(dimethylamino)thiocarbonyl]-thiocarbonohydrazone (A1110U). 348U87 inactivated herpes ribonucleotide reductase faster than did A1110U. Moreover, iron-complexed 348U87 was a considerably more potent inactivator than iron-complexed A1110U. It appeared to efficiently form an initial complex with the viral enzyme prior to rapid enzyme inactivation. The combination of 348U87 and iron-complexed 348U87 inactivated with a rate constant that was slightly greater than the sum of their individual rate constants of inactivation. The corresponding combination of A1110U species inactivated with a rate constant that was much greater than the sum of the individual rate constants of inactivation. Herpes ribonucleotide reductase that had been inactivated by either species of 348U87 was reactivated by diluting the enzyme and inactivators into assay medium containing excess iron. 348U87 was also an effective inactivator of herpes simplex virus type 2 and varicella zoster virus ribonucleotide reductases. The iron-complexed forms of 348U87 and A1110U exhibited very different modes of inactivation of human ribonucleotide reductase. Iron-complexed 348U87 was a tight-binding inactivator, whereas iron-complexed A1110U was only a weak, non-inactivating, inhibitor. Furthermore, the inactivation by iron-complexed 348U87 was not stimulated by either 348U87 or A1110U, whereas the weak inhibition by iron-complexed A1110U was converted to rapid inactivation by A1110U. Excess iron prevented the inactivation by iron-complexed 348U87. Uncomplexed 348U87 was similar to uncomplexed A1110U in that it was not an inhibitor of the human enzyme.
测定了2-乙酰吡啶5-[(2-氯苯胺基)-硫代羰基]-硫代碳酰肼（348U87）对单纯疱疹病毒1型和人核糖核苷酸还原酶的失活模式，并将其与先前[波特等人，《生物化学与药理学》39: 639 - 646，1990]所描述的2-乙酰吡啶5-[(二甲氨基)硫代羰基]-硫代碳酰肼（A1110U）的失活模式进行比较。348U87比A1110U更快地使疱疹核糖核苷酸还原酶失活。此外，铁络合的348U87是一种比铁络合的A1110U更有效的失活剂。在酶快速失活之前，它似乎能有效地与病毒酶形成初始复合物。348U87和铁络合的348U87的组合以略大于其各自失活速率常数之和的速率常数失活。A1110U同类物的相应组合以远大于其各自失活速率常数之和的速率常数失活。被348U87的任何一种同类物失活的疱疹核糖核苷酸还原酶，通过将酶和失活剂稀释到含有过量铁的测定培养基中可被重新激活。348U87也是单纯疱疹病毒2型和水痘带状疱疹病毒核糖核苷酸还原酶的有效失活剂。348U87和A1110U的铁络合形式对人核糖核苷酸还原酶表现出非常不同的失活模式。铁络合的348U87是一种紧密结合的失活剂，而铁络合的A1110U只是一种弱的、无失活作用的抑制剂。此外，铁络合的348U87的失活不受348U87或A1110U的刺激，而铁络合的A1110U的弱抑制作用被A1110U转变为快速失活。过量的铁可阻止铁络合的348U87的失活作用。未络合的348U87与未络合的A1110U相似，因为它不是人酶的抑制剂。
