Herold Susanna, Shivashankar Kalinga, Mehl Martin
Laboratorium für Anorganische Chemie, Eidgenössische Technische Hochschule, ETH Hönggerberg, CH-8093 Zürich, Switzerland.
Biochemistry. 2002 Nov 12;41(45):13460-72. doi: 10.1021/bi026046h.
We have analyzed in detail hemoglobin (Hb) and myoglobin (Mb) after treatment of different forms of these proteins with variable amounts of peroxynitrite. HPLC analyses of the peroxynitrite-treated proteins subjected either to acid hydrolysis or Pronase digestion showed that only very low quantities of 3-nitrotyrosine are formed when equivalent amounts of peroxynitrite are allowed to react with the oxy form of these proteins. Comparable amounts of nitrated amino acids are formed when metMb and metHb are treated with peroxynitrite under analogous conditions, but significantly larger yields are observed with apoMb and metMbCN. Interestingly, in addition we found that also the tryptophan residues of Mb and Hb are nitrated to a low but detectable extent. Taken together, our data suggest that the heme center of Mb may act as an efficient scavenger of peroxynitrite, protecting the globin from nitration. As peroxynitrite can irreversibly inhibit cytochrome c oxidase, oxyMb may utilize an additional important pathway to maintain mitochondrial respiration, that is, rapidly react with peroxynitrite and thus prevent nitration of other cellular components.
我们详细分析了用不同量过氧亚硝酸根处理这些蛋白质的不同形式后的血红蛋白（Hb）和肌红蛋白（Mb）。对经过过氧亚硝酸根处理的蛋白质进行酸水解或链霉蛋白酶消化后的HPLC分析表明，当等量的过氧亚硝酸根与这些蛋白质的氧合形式反应时，仅形成极少量的3-硝基酪氨酸。在类似条件下用过氧亚硝酸根处理高铁肌红蛋白（metMb）和高铁血红蛋白（metHb）时，会形成相当数量的硝化氨基酸，但脱辅基肌红蛋白（apoMb）和高铁氰化肌红蛋白（metMbCN）的产率明显更高。有趣的是，此外我们还发现Mb和Hb的色氨酸残基也会被硝化，程度虽低但可检测到。综上所述，我们的数据表明Mb的血红素中心可能作为过氧亚硝酸根的有效清除剂，保护球蛋白不被硝化。由于过氧亚硝酸根可不可逆地抑制细胞色素c氧化酶，氧合肌红蛋白（oxyMb）可能利用另一条重要途径来维持线粒体呼吸，即与过氧亚硝酸根快速反应，从而防止其他细胞成分被硝化。
