Role of oxygen and carbon radicals in hemoglobin oxidation.
Role of oxygen and carbon radicals in hemoglobin oxidation.
复制标题
氧和碳自由基在血红蛋白氧化中的作用。
DOI：
10.1006/abbi.1993.1205
复制
发表时间：
1993
影响因子：
3.9
通讯作者：
Lubin,BH
中科院分区：
文献类型：
--
作者：
Minetti,M;Mallozzi,C;Scorza,G;Scott,MD;Kuypers,FA;Lubin,BH
我们研究了自由基在血红蛋白（Hb）氧化和变性中的作用。为了产生自由基，我们使用了两种偶氮化合物，亲水性的2，2 ′-偶氮二（2-脒基丙烷盐酸盐）和疏水性的2，2 ′-偶氮二（2，4-二甲基戊腈）以及醌家族的药物吩嗪硫酸甲酯。用直接EPR和5，5-二甲基-1-吡咯啉-N-氧化物和N-叔丁基-α-苯基-硝酮的自旋捕集方法分析了自由基的种类。由偶氮化合物产生的自由基是碳自由基，并且在分子氧的存在下，是过氧基/烷氧基自由基。吩嗪与血红蛋白的反应产生了一个以氮为中心的半醌型自由基，只有在N2和活性氧（O.− 2和H2 O2）存在的情况下才能被EPR检测到。偶氮化合物氧化血红蛋白高铁血红蛋白，血红素和胆固醇，而吩嗪产生高铁血红蛋白和高铁血红蛋白。对于所有三种药物，低氧张力（pO 262毫米汞柱）增加了血红蛋白氧化产物的形成，而高氧张力（pO 2540毫米汞柱）减少血红蛋白氧化。形成不可逆的血红蛋白氧化产物（不可逆的血红素和血红蛋白交联），观察到只有与偶氮化合物，并减少在高pO 2。自旋陷阱和硫脲保护Hb的氧化损伤引起的偶氮化合物，而清除活性氧的酶，如超氧化物歧化酶和过氧化氢酶，影响Kb氧化诱导的吩嗪和疏水性的偶氮化合物。这些结果表明每种试剂的氧化和变性模式不同。由吩嗪引起的损伤依赖于活性氧的形成，而由偶氮化合物引起的损伤主要是由于碳中心自由基与活性氧的参与，只有疏水性偶氮化合物。血红蛋白与药物自由基清除分子氧的优先相互作用表明，这种蛋白质在缺氧条件下可能更具反应性，并导致认为，良好的氧供应可以提供一个重要的防御药物诱导的血红蛋白氧化。
We investigated the role of free radicals in hemoglobin (Hb) oxidation and denaturation. To generate free radicals, we used two azocompounds, the hydrophilic 2,2′-azobis(2-amidinopropane hydrochloride and the hydrophobic 2,2′-azobis(2,4-dimethylvaleronitrile) and a drug of the quinone family, phenazine methosulfate. The radical species involved were analyzed by direct EPR and spin trapping with 5,5-dimethyl-1-pyrrolineN-oxide, andN-t-butyl-α-phenyl-nitrone. The free radicals generated by the azocompounds were carbon radicals and, in the presence of molecular oxygen, peroxyl/alkoxyl radicals. The reaction of phenazine with Hb produced a nitrogen-centered semiquinoid radical detectable by EPR only under N2and reactive oxygen species (O.−2and H2O2) in the presence of molecular oxygen. Azocompounds oxidized Hb to methemoglobin, hemichromes, and choleglobin while phenazine produced methemoglobin and ferrylhemoglobin. For all three drugs, low oxygen tensions (pO262 mm Hg) increased the formation of Hb oxidation products, whereas high oxygen tensions (pO2540 mm Hg) reduced Hb oxidation. The formation of irreversible Hb oxidation products (irreversible hemichromes and Hb cross-linking) was observed only with the azocompounds and was reduced at highpO2. Spin traps and thiourea protected Hb from the oxidative damage induced by the azocompounds, whereas enzymes scavenging reactive oxygen species, such as superoxide dismutase and catalase, affected Kb oxidation induced by phenazine and that induced by the hydrophobic azocompound. These results indicate distinct patterns of oxidation and denaturation with each agent. Damage induced by phenazine was dependent on the formation of reactive oxygen species, whereas the damage induced by the azocompounds was due mainly to carbon-centered radicals with some involvement by reactive oxygen species only for the hydrophobic azocompound. The preferential interaction of Hb with drug radicals scavenged by molecular oxygen indicates that this protein may be more reactive under hypoxic conditions and led to the view that a good supply of oxygen can provide an important defense against drug-induced Hb oxidation.