Nitrogen-15 nuclear magnetic resonance studies of iron-bound cyanide(nitrogen-15)(1-) ion in ferric low-spin cyanide complexes of various porphyrin derivatives and various hemoproteins
Nitrogen-15 nuclear magnetic resonance studies of iron-bound cyanide(nitrogen-15)(1-) ion in ferric low-spin cyanide complexes of various porphyrin derivatives and various hemoproteins
复制标题
各种卟啉衍生物和各种血红素蛋白的铁低自旋氰化物络合物中铁结合氰化物(氮-15)(1-)离子的氮15核磁共振研究
DOI：
10.1021/ja00479a046
复制
发表时间：
1978
影响因子：
15
通讯作者：
T. Inubushi
中科院分区：
文献类型：
--
作者：
I. Morishima;T. Inubushi
本文报道了各种卟啉衍生物和血红素蛋白的低自旋铁氰化物络合物中~（15）N标记氰化物的~（15）N顺磁位移的研究。与血红素-铁原子配位的C15 N的15 N共振可以与C15 N-的体共振分开检测，并且各种氯化血红素和血红素蛋白的15 N化学位移相对于内部15 NO3-在448至1070 ppm的范围内。顺式和反式配体上的15 N位移的单和二氰基配合物的原，氘，内消旋，hemato-，和octagethyl卟啉的影响也进行了研究。由轴向配体的变化引起的反式效应比由卟啉周边基团取代引起的顺式效应显著得多。细胞色素c、肌红蛋白和血红蛋白的氰化物复合物中铁结合氰化物15 N位移的实质性差异主要解释为这种反式效应，即近端组氨酸-铁结合性质的微妙变化的效应。cvanohemincomplex的~（15）N各向同性位移对溶剂也很敏感。质子供体溶剂在引起C15 N位移的高场偏置方面最有效。pH值变化引起的15 N位移与末端组氨酸和血红素结合的氰化物之间可能存在的氢键有关，血红素蛋白中辅基的环境结构一直是生物化学家和化学家们感兴趣的问题。近年来，质子核磁共振波谱已成为研究血红素蛋白结构的有力工具，特别是在阐明血红素的电子状态、表征配体结合情况以及研究血红素-脱辅基蛋白相互作用等方面。2这些研究大多涉及血红素蛋白或模型化合物中卟啉周边取代基的质子各向同性移动。
Studies on, 5N paramagnetic shifts of the iron-bound 15N-labeled cyanide in low-spin ferric cyanide complexes of various porphyrin derivatives and hemoproteins are reported. The 15N resonance of C15N coordinated to the heme-iron atom can be separately detected from the bulk resonance of C15N “, and the 15N chemical shifts for various hemin and hemoproteins range from 448 to 1070 ppm with respect to internal l5N03~. The cis and trans ligand effects on the 15N shifts for the mono-and dicyano complexes of proto-, deutero-, meso-, hemato-, and octaethylporphyrins are also investigated. The trans effect induced by a change in the axial ligand is much more pronounced than the cis effect caused by substitution of the porphyrin pe-ripheral groups. A substantial difference in theiron-bound cyanide l5N shifts in the cyanide complexes of cytochrome c, myoglobin, and hemoglobin was primarily interpretedin terms of this trans effect, the effect of subtle changes in the proximal histidine-Fe bindingnature. The l5N isotropic shifts for cvanohemincomplexes are also shown to be very sensitive to solvent. Proton donor solvents were most effective in causing upfield bias of the CI5N-shift. The sizable 15N shift induced by pH variation for cyanomyoglobin was interpreted in relation to possible involvement of hydrogen bonding between distal histidine and heme-bound cyanide.The environmental structure of the prosthetic group in hemoproteins has long been a problem of keen andcontinuous interest to biochemists and chemists alike. In recentyears proton NMR spectroscopy, among many physical methods, has become a powerful tool for structural studies of hem-oproteins, particularly in elucidating electronic states of the heme, characterizing the ligand binding situation, and delin-eating the heme-apoprotein interaction. 2 Mostof these studies have dealt with the proton isotropicshift of peripheral por-phyrin substituents inthe hemoproteins or in model com-pounds.