Structure and kinetics of formation of catechol complexes of ferric soybean lipoxygenase-1.
Structure and kinetics of formation of catechol complexes of ferric soybean lipoxygenase-1.
复制标题
铁大豆脂氧合酶-1 形成儿茶酚复合物的结构和动力学。
DOI：
10.1021/bi00046a030
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Scarrow,RC
中科院分区：
文献类型：
--
作者：
Nelson,MJ;Brennan,BA;Chase,DB;Cowling,RA;Grove,GN;Scarrow,RC
修订稿于 1995 年 8 月 21 日收到®摘要：三价铁大豆脂氧合酶与 4-取代儿茶酚形成稳定的复合物。通过共振拉曼、电子顺磁共振、可见光和X射线光谱研究了酶与3,4-二羟基苯甲腈之间的复合物的结构。它是一种具有至少一个水配体的二齿铁-儿茶酚盐络合物。通过停流光谱研究了脂氧合酶与3, 4-二羟基苯甲腈和3, 4-二羟基苯乙酮之间形成复合物的动力学。数据与两个动力学上不同的可逆步骤一致。第一步的 pH 依赖性表明反应的底物是儿茶酚单阴离子。当这些结果结合起来时，提出了络合反应的合理机制。大豆脂氧合酶同工酶 1 是一种非血红素铁酶，可催化双氧与亚油酸的加成，在 pH 9 时产生 (135)-9, 11 (Z,£)-十八碳二烯酸 (13 (S)-HPOD1) 作为主要产物（Gardner，1991；西多，1991）。该酶与其他单核非血红素铁加氧酶（例如，脯氨酸羟化酶、儿茶酚双加氧酶和异青霉素N合酶）不同，因为0-0键在反应过程中不被裂解。非血红素铁加氧酶中的金属离子似乎与催化密切相关。因此，脂氧合酶反应的独特性可能在很大程度上是由于其铁位点反应性的差异造成的。活性铁脂加氧酶 (SLOA) 中铁位点的模型如图 1 所示。组氨酸、羧酸盐和天冬酰胺配体的特性源自亚铁脂加氧酶的晶体结构
Revised Manuscript Received August 21, 1995® abstract: Ferric soybean lipoxygenase forms stable complexes with 4-substituted catechols. The stmcture of the complex betweenthe enzyme and 3, 4-dihydroxybenzonitrile has been studied by resonance Raman, electron paramagnetic resonance, visible, and X-ray spectroscopies. It is a bidentate iron—catecholate complex with at least one water ligand. The kinetics of formation of complexes between lipoxygenase and 3, 4-dihydroxybenzonitrile and 3, 4-dihydroxyacetophenone have been studied by stopped-flow spectroscopy. The data are consistent with two kinetically distinct, reversible steps. The pH dependence of the first step suggests that the substrate for the reaction is the catechol monoanion. When these results are combined, plausible mechanisms for the complexation reaction are suggested.Soybean lipoxygenase isozyme 1 is a non-heme iron enzyme that catalyzes the addition of dioxygen to linoleic acid, yielding (135)-9, 11 (Z,£)-octadecadienoic acid (13 (S)-HPOD1) as the dominant product at pH 9 (Gardner, 1991; Siedow, 1991). This enzyme stands in contrast to the other mononuclear non-heme iron oxygenases (eg, proline hydroxylase, catechol dioxygenases, and isopenicillin N synthase) in thatthe 0—0 bond is not cleaved during the reaction. The metal ion in the non-heme iron oxygenases appears to be intimately involved in catalysis; consequently, the uniqueness of the lipoxygenase reaction presumably results in large part from differences in the reactivity of its iron site. A model for the iron site in active, ferric lipoxygenase (SLOA) is shown in Figure 1. The identities of the histidine, carboxylate, and asparagine ligands are derived from the crystal structure of ferrous lipoxygenase