Photochemically modified myeloperoxidase, with optical spectral properties analogous to those of lactoperoxidase, retains its original catalytic activity.
Photochemically modified myeloperoxidase, with optical spectral properties analogous to those of lactoperoxidase, retains its original catalytic activity.
复制标题
光化学修饰的髓过氧化物酶具有与乳过氧化物酶类似的光谱特性，保留了其原有的催化活性。
DOI：
10.1021/bi00482a023
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Ikeda-Saito,M
中科院分区：
文献类型：
--
作者：
Hori,H;Ikeda-Saito,M
凯斯西储大学医学院生理与生物物理系，俄亥俄州克利夫兰44106摘要：在紫外光下，利用酮光还原生成的基自由基进行还原反应的过程中，发现了髓过氧化物酶中发色团的光诱导化学修饰。该修饰酶的光吸收和共振拉曼光谱显示为铁卟啉发色团。修饰酶的碱性吡啶血色素与原卟啉铁IX的光谱密切相关。用甲氧基将修饰后的髓过氧化物酶的发色团从蛋白上切割下来。提取的血红素基团的抗磁性双（氰化物）化合物的质子磁共振显示存在与卟啉大环相关的两个乙烯基和三个甲基侧链。这些数据为髓过氧化物酶活性位点的结构提供了进一步的见解。天然髓过氧化物酶的EPR光谱性质和酶活性在修饰酶中基本保守。我们目前的结果表明，血红素外周取代基被修饰，而围绕发色团的立体化学结构没有被光化学修饰改变。髓过氧化物酶是多态核中性粒细胞抗菌系统的主要组成部分（k黎巴嫩off & Clark， 1978）。髓过氧化物酶的一个独特特性是它能够催化过氧化氢和氯离子形成次氯酸（Harrison& Schultz, 1976）。尽管对髓过氧化物酶的光谱和酶学性质进行了许多研究（Schultz, 1980），但由于无法通过常规方法从酶蛋白中提取血红素假体，可能是由于血红素基团与载脂蛋白之间的共价键，因此迄今为止尚未确定该酶中血红素基团的化学结构。然而，对于这种酶的血红素群的化学结构，有几种建议
Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 Received February 9, 1990; Revised Manuscript Received April 11, 1990 abstract: During the course of a reducing reaction using ketyl radicals generated from ketone photoreduction with ultraviolet light, a photoinduced chemical modification of the chromophore group in myeloperoxidase has been found. Light absorption and resonance Raman spectra for this modified enzyme indicated an iron porphyrin chromophore group. The alkaline pyridine hemochrome of the modified enzyme exhibited an optical spectrum closely related to that of iron protoporphyrin IX. The chromophore group of the modified myeloperoxidase was cleaved from the protein by methoxide. Proton magnetic resonance of the diamagnetic bis (cyanide) compound of the extracted heme group showed the presence of two vinyl and three methyl side chains associated with a porphyrin macrocycle. These data provide further insight into the structure of the active site in myeloperoxidase. The EPR spectral properties and enzymatic activities of the native myeloperoxidase are essentially conserved in the modified enzyme. Our present results indicate that the heme peripheral substituent is modified while the stereochemical structure surrounding the chromophore group is not altered by the photochemical modification.IN^ yeloperoxidase is a major component of the antimicrobial system of polymorphonuclearneutrophils (Klebanoff & Clark, 1978). One of the unique properties of myeloperoxidase is its ability to catalyze the formation of hypochlorous acid from hydrogen peroxide and chloride ion (Harrison& Schultz, 1976). Despite many investigations of the spectroscopic and enzymatic properties of myeloperoxidase (Schultz, 1980), the chemical structure of the heme group in this enzyme has not so far been identified because of the inability to extract the heme prosthetic group from the enzyme protein by usual methods, possibly due to the covalent linkage between the heme group and the apoprotein. Nevertheless, several proposals for the chemical structure of the heme group of this enzyme have