Epoxidation of styrene by hemoglobin and myoglobin. Transfer of oxidizing equivalents to the protein surface.
Epoxidation of styrene by hemoglobin and myoglobin. Transfer of oxidizing equivalents to the protein surface.
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DOI：
10.1016/s0021-9258(17)39362-6
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发表时间：
1985-08
期刊：
影响因子：
--
通讯作者：
P. Ortiz de Montellano;C E Catalano
中科院分区：
文献类型：
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作者：
P. Ortiz de Montellano;C E Catalano
高铁血红蛋白和高铁肌红蛋白催化苯乙烯氧化成氧化苯乙烯和苯甲醛。氧化苯乙烯的形成需要分子氧和H2 O2，但抑制剂研究表明，不涉及超氧化物或羟基自由基。氧化苯乙烯中大约38%、67%和78%的氧分别来自牛血红蛋白、抹香鲸肌红蛋白和马心肌红蛋白催化的反应中的18 O2，而70%、55%和35%的氧可以证明来自[18 O] H2 O2。然而，比标记数据所表明的更大比例的环氧化物氧（也许全部）来自分子氧而不是H2 O2，因为血红蛋白从过氧化物中产生分子氧。通过高铁血红蛋白的苯乙烯的环氧化得到等量的R和S对映异构体，并且如反式-[1- 2 H]苯乙烯的研究所示，进行部分（33%）的烯烃立体化学损失。该结果是合理的H2 O2依赖形成的蛋白质自由基，结合分子氧，得到一个蛋白质过氧自由基，氧化苯乙烯。
Methemoglobin and metmyoglobin catalyze the H2O2-dependent oxidation of styrene to styrene oxide and benzaldehyde. The formation of styrene oxide requires molecular oxygen as well as H2O2 but does not, as shown by inhibitor studies, involve the superoxide or hydroxyl radicals. Approximately 38, 67, and 78% of the oxygen in styrene oxide derives from 18O2 in the reactions catalyzed, respectively, by bovine hemoglobin, sperm whale myoglobin, and equine heart myoglobin, whereas 70, 55, and 35% of the oxygen can be shown to be derived from [18O]H2O2. However, a larger fraction of the epoxide oxygen than suggested by the labeling data (perhaps all) derives from molecular oxygen rather than H2O2 because the hemoproteins produce molecular oxygen from the peroxide. The epoxidation of styrene by methemoglobin gives equal amounts of the R and S enantiomers and, as shown by studies with trans-[1-2H]styrene, proceeds with partial (33%) loss of the olefin stereochemistry. The results are rationalized by H2O2-dependent formation of a protein radical that combines with molecular oxygen to give a protein-peroxy radical that oxidizes styrene.