Multinuclear magnetic resonance studies of the 2Fe.cntdot.2S* ferredoxin from Anabaena species strain PCC 7120. 3. Detection and characterization of hyperfine-shifted nitrogen-15 and hydrogen-1 resonances of the oxidized form
Multinuclear magnetic resonance studies of the 2Fe.cntdot.2S* ferredoxin from Anabaena species strain PCC 7120. 3. Detection and characterization of hyperfine-shifted nitrogen-15 and hydrogen-1 resonances of the oxidized form
复制标题
对来自鱼腥藻菌株 PCC 7120 的 2Fe.cntdot.2S* 铁氧还蛋白进行多核磁共振研究。 3. 氧化形式的超精细位移氮 15 和氢 1 共振的检测和表征
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
J. Markley
中科院分区：
文献类型：
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作者：
B. Oh;J. Markley
通过一系列的异核二维实验，确定了Anabaena sp.菌株PCC 7120氨基酸侧链上的所有氮信号和氧化态2Fe{center dot}2S*铁氧化蛋白98个主氮信号中的80个。在一维{sup 15}N核磁共振光谱中观察到两个额外的氮信号，并将其分类为质子共振经历顺磁拓宽的残基的主酰胺共振。一维{sup 15}N核磁共振谱显示出9个超精细位移和加宽的共振。从抗磁氮信号和相关铁氧还蛋白的可用x射线坐标来看，解析的超精细位移{sup 15}N峰归因于与2Fe{center dot}2S*中心共享电子的另外两种氨基酸的主酰胺氮到靠近2Fe{center dot}2S*中心的另外两种氨基酸的主酰胺氮。丢失和无法解释的7个N信号可能隐藏在酰胺信号的包络层之下。所有直接与7个缺失氮和9个超精细位移氮相连的酰胺质子的氢核磁共振信号太宽，无法在常规的二维核磁共振光谱中分辨。从它们对磁回比的依赖性来看，{sup 1}H共振的宽度应该是经历类似超精细相互作用的{sup 15}N共振的100倍。这似乎就是为什么观察到更多的高分辨超精细位移{sup 15}N共振比相应的{sup 1}H共振的原因。结果表明，超精细位移{sup 15}N峰可以提供一个独特的窗口，了解这个和其他顺磁中心的电子结构和环境。«少
All the nitrogen signals from the amino acid side chains and 80 of the total of 98 backbone nitrogen signals of the oxidized form of the 2Fe{center dot}2S* ferredoxin from Anabaena sp. strain PCC 7120 were assigned by means of a series of heteronuclear two-dimensional experiments. Two additional nitrogen signals were observed in the one-dimensional {sup 15}N NMR spectrum and classified as backbone amide resonances from residues whose proton resonances experience paramagnetic broadening. The one-dimensional {sup 15}N NMR spectrum shows nine resonances that are hyperfine shifted and broadened. From this inventory of diamagnetic nitrogen signals and the available X-ray coordinates of the related ferredoxin, the resolved hyperfine-shifted {sup 15}N peaks were attributed to backbone amide nitrogens of two other amino acids that share electrons with the 2Fe{center dot}2S* center to backbone amide nitrogens of two other amino acids that are close to the 2Fe{center dot}2S* center. The seven {sup 15}N signals that are missing and unaccounted for probably are buried under the envelope of amide signals. {sup 1}H NMR signals from all the amide protons directly bonded to the seven missing and nine hyperfine-shifted nitrogens were too broad to be resolved in conventional 2D NMR spectra. From their dependence onmore » the magnetogyric ratio, a {sup 1}H resonance should be up to 100 times broader than a {sup 15}N resonance that experiences a similar hyperfine interaction. This appears to be the reason why more well-resolved hyperfine-shifted {sup 15}N resonances were observed than corresponding {sup 1}H resonances. The result suggest that hyperfine-shifted {sup 15}N peaks can provide a unique window on the electronic structure and environment of this and other paramagnetic centers.« less