Subunit interactions change the heme active-site geometry in p-cresol methylhydroxylase.
Subunit interactions change the heme active-site geometry in p-cresol methylhydroxylase.
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亚基相互作用改变对甲酚甲基羟化酶中血红素活性位点的几何形状。
DOI：
10.1073/pnas.88.21.9463
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发表时间：
1991
影响因子：
11.1
通讯作者：
Hill,HA
中科院分区：
文献类型：
--
作者：
McLendon,GL;Bagby,S;Charman,JA;Driscoll,PC;McIntire,WS;Mathews,FS;Hill,HA
对甲酚甲基羟化酶[4-甲酚（受体）氧化还原酶（甲基羟化），EC 1.17.99.1]含有两个亚基：细胞色素c（电子转移）亚基（细胞色素cpc）和黄素（催化）亚基。当这些亚基通过等电聚焦分离时，得到一个稳定的细胞色素亚基。氧化的细胞色素cpc与氧化的对甲酚甲基羟化酶的一维NMR谱有显著差异。还原细胞色素cpc的二维核Overhauser增强和交换光谱（NOESY）分析表明，当细胞色素cpc与黄素亚基结合时，稳定亚基的轴向配体Met-50围绕C - γ - s - δ键旋转定向。这种重定向必然导致血红素键的变化，这反映在顺磁位移的共振和氧化还原电位中。因此，对甲酚甲基羟化酶提供了亚基相互作用与活性位点结构和反应性耦合的有趣例子。
The enzyme p-cresol methylhydroxylase [4-cresol: (acceptor) oxidoreductase (methyl-hydroxylating), EC 1.17.99.1] contains two subunits: a cytochrome c (electron transfer) subunit (cytochrome cpc) and a flavin (catalytic) subunit. When these subunits are separated by isoelectric focusing, a stable cytochrome subunit is obtained. Significant differences are observed between the one-dimensional NMR spectra of oxidized cytochrome cpc and of oxidized p-cresol methylhydroxylase. Analysis of the two-dimensional nuclear Overhauser enhancement and exchange spectroscopy (NOESY) spectrum of reduced cytochrome cpc suggests that the axial ligand, Met-50, of the stable subunit reorients by a rotation about the C gamma-S delta bond when cytochrome cpc binds to the flavin subunit. This reorientation must result in a change in bonding at the heme, which is reflected both in the para-magnetically shifted resonances and in the redox potential. p-Cresol methylhydroxylase thereby provides an interesting example of the coupling of subunit interactions to active-site structure and reactivity.