CATALYTIC MECHANISMS OF HEME ENZYMES

血红素酶的催化机制

• 批准号: 6490155
• 负责人: MASAO IKEDA-SAITO
• 金额: $ 22.86万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6490155
• 关键词: Raman spectrometry; X ray spectrometry; active sites; carbon monoxide; electron nuclear double resonance spectroscopy; electron spin resonance spectroscopy; enzyme complex; enzyme mechanism; heme oxygenase; iron compounds; metalloporphyrins; oxidoreductase inhibitor

The objective of the proposed research is to elucidate the catalytic mechanism of heme oxygenase which carries out a oxidative degradation of iron protoporphyrin IX (hemin) into iron (Fe), carbon monoxide (CO), and biliverdin IXalpha. In the proposed research, the catalytic intermeditates will be prepared by using chemically synthesized alpha- hydroxyheme and verdoheme. Electronic and molecular structures of the alpha-hydroxyheme and verdoheme intermediates will be examined by optical absorption, EPR, resonance Raman, and X-ray spectroscopy. To do this, we are combining resources and skills of the research groups at Case Western Reserve Univ., Albert Einsterin College of Medicine, Rice Univ., Yamagata Univ., Riken, Argonne National Lab., and Stanford Synchrotron Radiation Lab. for an efficient utilization of the power of mergining protein engineering, porphyrin synthesis, and advanced spectroscopic techniques. In this project several specific questions concerning the structure, function and mechanisms of heme oxygenase will be addressed. How the enzyme activates molecular oxygen at each step of three mono-oxygenase cycle will be determined; how the enzyme functions when it is bound by CO, its product, will be examined; mechanisms of inhibiting the enzyme will be determined; and the catalytic mechanism will be clarified. In addition to the well- established role of heme oxygenase as a key enzyme of heme catabolism, CO and biliverdine, the products of the enzyme, are now recognized to play significant physiological functions as a free-radical scavenger and a versatile physiological messenger in neurotransmission and vasodilation, respectively. Thus, the mechanism of biliverdin and CO generation and control are of utmost biomedical importance.

拟议研究的目的是阐明催化 血红素加氧酶进行氧化降解的机制 铁原卟啉 IX（氯化血红素）转化为铁 (Fe)、一氧化碳 (CO)、 和胆绿素IXα。 在拟议的研究中，催化 中间体将通过使用化学合成的α-来制备 羟基血红素和绿色血红素。的电子和分子结构 α-羟基血红素和绿血红素中间体将由 光学吸收、EPR、共振拉曼和 X 射线光谱。 到 为此，我们正在结合研究小组的资源和技能 凯斯西储大学阿尔伯特爱因斯坦医学院 莱斯大学、山形大学、理化学研究所、阿贡国家实验室和斯坦福大学 同步辐射实验室。为了有效利用电力 融合蛋白质工程、卟啉合成和先进技术 光谱技术。 在这个项目中几个具体问题 血红素加氧酶的结构、功能和机制 得到解决。 酶如何在每个步骤中激活分子氧 将确定三个单加氧酶循环；酶如何 将检查其与 CO（其产物）结合时的功能； 将确定抑制酶的机制；和 催化机制将得到阐明。 除了良好的 确定了血红素加氧酶作为血红素分解代谢的关键酶的作用， CO 和胆绿定（酶的产物）现在被认为可以 作为自由基清除剂发挥重要的生理功能 神经传递中的多功能生理信使 分别具有血管舒张作用。 因此，胆绿素和CO的作用机制 产生和控制具有极其重要的生物医学意义。

项目成果

Molecular oxygen oxidizes the porphyrin ring of the ferric alpha-hydroxyheme in heme oxygenase in the absence of reducing equivalent.

在没有还原当量的情况下，分子氧氧化血红素加氧酶中三价铁α-羟基血红素的卟啉环。

• DOI: 10.1016/s0167-4838(99)00097-7
• 发表时间: 1999
• 期刊: Biochimica et biophysica acta
• 作者: Migita,CT;Fujii,H;MansfieldMatera,K;Takahashi,S;Zhou,H;Yoshida,T
• 通讯作者: Yoshida,T

The crystal structures of the ferric and ferrous forms of the heme complex of HmuO, a heme oxygenase of Corynebacterium diphtheriae

• DOI: 10.1074/jbc.m311631200
• 发表时间: 2004-03-19
• 期刊: JOURNAL OF BIOLOGICAL CHEMISTRY
• 影响因子: 4.8
• 作者: Hirotsu, S;Chu, GC;Ikeda-Saito, M
• 通讯作者: Ikeda-Saito, M

Stereoselectivity of each of the three steps of the heme oxygenase reaction: hemin to meso-hydroxyhemin, meso-hydroxyhemin to verdoheme, and verdoheme to biliverdin.

血红素加氧酶反应三个步骤中每一步的立体选择性：血红素到内消旋羟基血红素、内消旋羟基血红素到绿血红素、以及绿血红素到胆绿素。

• DOI: 10.1021/bi027173g
• 发表时间: 2003
• 期刊: Biochemistry
• 影响因子: 2.9
• 作者: Zhang,Xuhong;Fujii,Hiroshi;Matera,KathrynMansfield;Migita,CatharinaTaiko;Sun,Danyu;Sato,Michihiko;Ikeda-Saito,Masao;Yoshida,Tadashi
• 通讯作者: Yoshida,Tadashi