Nakamura S, Nakamura M, Yamazaki I, Morrison M
J Biol Chem. 1984 Jun 10;259(11):7080-5.
Lactoperoxidase in the ferryl state (compound II) reacts with sulfide to form a typical sulfheme -containing hemoprotein as do hemoglobin, myoglobin, and catalase. Ferrous sulflactoperoxidase is primarily formed and then oxidized to its ferric form under aerobic conditions. Similar reactions of lactoperoxidase occurs when methylmercaptoimidazole (MMI) is substituted for sulfide. The yield of the adducts from one-turnover reactions of ferryl lactoperoxidase is 100% with sulfide and about 20% with MMI. Sulfur and MMI of the adducts appear to be removed from the enzyme upon reduction by dithionite. Upon the reactions with cysteine and dithiothreitol, the enzyme is converted to spectral species, which are less characteristic but are similar to ferrous and ferric sulflactoperoxidases , respectively. We conclude that there is no essential difference in the mechanism of reactions of lactoperoxidase with sulfide, MMI, cysteine, and dithiothreitol.
高铁血红素状态的乳过氧化物酶（化合物II）与硫化物反应，形成一种典型的含硫血红素血红蛋白，血红蛋白、肌红蛋白和过氧化氢酶也是如此。亚铁硫代乳过氧化物酶首先形成，然后在有氧条件下氧化为其三价铁形式。当用甲基巯基咪唑（MMI）代替硫化物时，乳过氧化物酶会发生类似反应。高铁乳过氧化物酶单周转反应生成加合物的产率，与硫化物反应时为100%，与MMI反应时约为20%。加合物中的硫和MMI在连二亚硫酸盐还原后似乎从酶中去除。在与半胱氨酸和二硫苏糖醇反应时，该酶转化为光谱物种，它们的特征性较弱，但分别类似于亚铁硫代乳过氧化物酶和高铁硫代乳过氧化物酶。我们得出结论，乳过氧化物酶与硫化物、MMI、半胱氨酸和二硫苏糖醇反应的机制没有本质区别。
