HIGH-RESOLUTION PROTON NUCLEAR MAGNETIC-RESONANCE STUDIES OF THE NICKEL(II) DERIVATIVE OF AZURIN
HIGH-RESOLUTION PROTON NUCLEAR MAGNETIC-RESONANCE STUDIES OF THE NICKEL(II) DERIVATIVE OF AZURIN
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DOI：
10.1021/bi00267a033
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发表时间：
1982-01-01
期刊：
影响因子：
2.9
通讯作者：
MCMILLIN, DR
中科院分区：
文献类型：
--
作者：
BLASZAK, JA;ULRICH, EL;MCMILLIN, DR
报道了镍（II）天青蛋白（来自铜绿假单胞菌的蓝铜蛋白天青蛋白）的镍（II）衍生物的高分辨率（360和470 MHz）1H NMR研究。Ni（II）天青的脂族共振与脱辅基天青和Cu（I）天青的脂族共振密切平行，表明Ni（II）的结合没有重大的结构变化。Ni（II）天青的磁矩（μ eff = 3.2 μ B）与类似Cu（I）天青的假四面体配位环境一致。来自配体部分的质子的共振从4，4-二甲基-4-硅戊烷-1-磺酸盐向低场移动125 ppm，并且由于Ni中心的内部场而向高场移动20 ppm。这些强烈位移的共振之一被分配到甲硫氨酸配体的甲基质子。从Ni（II）天青的光谱作为pH的函数，测得组氨酸-35和组氨酸-83的pKa值为apx。6.0分别为7.5。组氨酸-35以不连续的方式被取代，并且显著地，几个各向同性移动的配体质子也以不连续的方式被取代，同样在相同pHmid的实验误差内。该结果加强了这样的建议，即与组氨酸-35的质子化偶联的构象变化在调节天然天青蛋白的电子转移反应中起重要作用（Silvestrini，M. C.等，1981年）。
High-resolution of (360 and 470 MHz) 1H NMR studies of Ni(II) azurin, the Ni(II) derivative of the blue copper protein azurine [from Pseudomonas aeruginosa], are reported. The aliphatic resonances of Ni(II) azurin, closely parallel those of apoazurin and Cu(I) azurin, and indicate that no major structural changes are associated with the binding of Ni(II). The magnetic moment of Ni(II) azurin (.mu.eff = 3.2 .mu.B) is in keeping with a pseudotetrahedral coordination environment like that of Cu(I) azurin. Resonances of protons from the ligand moieties are shifted as far as 125 ppm downfield from 4,4-dimethyl-4-silapentane-1-sulfonate and as far as 20 ppm upfield by internal fields due to the Ni center. One of these strongly shifted resonances is assigned to the methyl protons of the methionine ligand. From spectra of Ni(II) azurin as a function of pH, the pKa'' values of histidine-35 and histidine-83 were measured to be .apprx. 6.0 and 7.5, respectively. Histidine-35 titrates in a discontinuous fashion, and, significantly, so do several of the isotropically shifted ligand protons, also within experimental error with the same pHmid. This result reinforces the suggestion that the conformational change coupled to the protonation of histidine-35 plays an important role in regulating electron transfer reactions of native azurin (Silvestrini, M. C. et al., 1981).