Proton NMR studies of the electronic and molecular structure of ferric low-spin horseradish peroxidase complexes
Proton NMR studies of the electronic and molecular structure of ferric low-spin horseradish peroxidase complexes
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三价铁低自旋辣根过氧化物酶复合物的电子和分子结构的质子核磁共振研究
DOI：
10.1021/ja00328a025
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发表时间：
1984
影响因子：
15
通讯作者：
K. Langry
中科院分区：
文献类型：
--
作者：
J. Ropp;G. N. Mar;Kevin M Smith;K. Langry
用天然和重组辣根过氧化物酶(HRP)的高场质子核磁共振研究了三种铁低自旋形式的蛋白质中血红素口袋的电子和物理结构。选择性地将氚标记的氯化血红素重新组合成apo-HRP导致了许多超精细移动峰的确定归属。考虑到线宽、pH滴定数据和血红素外围取代基的影响，可以指定额外的血红素以及近端的组氨酸峰。变温数据进一步证明HRP中存在紧密的血红素-载脂蛋白接触。结果表明，在高pH条件下，HRP的氰络合物向新的氰基连接碱性形式的转变与轴向磁各向异性的变化是一致的。在高pH静息状态下，HRP的光谱和结构发生了更剧烈的变化，这归因于远端组氨酸的配位，其咪唑去质子化，其平面基本上垂直于近端组胺基咪唑的构型。
High-field proton NMR studies of native and reconstituted horseradish peroxidase (HRP) were used to investigate the electronic and physical structure of the heme pocket in three ferric low-spin forms of the protein. Reconstitution of selectively deuterium labeled hemes into apo-HRP led to the definitive assignment of many hyperfine shifted peaks. Consideration of line width, pH titration data, and the effect of heme peripheral substituents has permitted the assignment of additional heme as well as proximal histidine peaks. Variable temperature datapresent further evidence of tight heme-apoprotein contacts in HRP. It is shown that the transition of the cyanide complex of HRP at highpH to a new cyanide-ligated alkaline form is consistent with a change in axial magnetic anisotropy. At high pH resting state HRP undergoes a more drastic change in spectrum and structure that is attributed to coordination of a distal histidine in a configuration with its imidazole deprotonated and its plane oriented essentially perpendicular to that of the proximal histidyl imidazole.