Nitric oxide is known to be a messenger in animals and plants. It may act either as a pro-oxidant or antioxidant. In the present work, the yeast Saccharomyces cerevisiae was treated under aerobic conditions with the nitric oxide donor, sodium nitroprusside (SNP), at concentrations of 1, 5 and 10 mM. The activities of antioxidant enzymes as well as concentrations of protein carbonyls and cellular thiols were measured. Yeast incubation with SNP increased the activities of catalase and superoxide dismutase. Cycloheximide, an inhibitor of translation, blocked SNP-induced catalase activation, but not SOD activation. Incubation with SNP increased the activity of peroxisomal catalase, whereas cytosolic catalase was not affected. SNP treatment inactivated aconitase in a dose-dependent manner. Surprisingly, in cells incubated with 1 mM SNP, the levels of low-molecular weight thiols were significantly higher, whereas the concentrations of protein carbonyl groups were lower than those in untreated cells. The incubation of yeast cells either with decomposed SNP or with SNP under anaerobic conditions did not result in SOD and catalase activation. It is suggested, that under aerobic conditions, the SNP effects are connected with induction of mild oxidative/nitrosative stress.

中文翻译：

---

硝普钠在酿酒酵母中诱导轻度的氧化应激。

一氧化氮是动植物的信使。它可以充当助氧化剂或抗氧化剂。在目前的工作中，在好氧条件下用浓度为1、5和10 mM的一氧化氮供体硝普钠（SNP）处理啤酒酵母。测量了抗氧化酶的活性以及蛋白羰基和细胞硫醇的浓度。酵母与SNP的孵育增加了过氧化氢酶和超氧化物歧化酶的活性。Cycloheximide，一种翻译抑制剂，可以阻断SNP诱导的过氧化氢酶活化，但不能阻断SOD活化。与SNP一起孵育可增加过氧化物酶过氧化氢酶的活性，而胞质过氧化氢酶则不受影响。SNP治疗以剂量依赖性方式使乌头酸酶失活。令人惊讶的是，在用1 mM SNP孵育的细胞中，低分子量硫醇的水平显着较高，而蛋白质羰基的浓度低于未处理细胞。用分解的SNP或在厌氧条件下用SNP孵育酵母细胞不会导致SOD和过氧化氢酶活化。建议在有氧条件下，SNP效应与诱导轻度氧化/亚硝化应力有关。