Zeng Weiqiao, Silvernail Nathan J, Wharton David C, Georgiev Georgi Y, Leu Bogdan M, Scheidt W Robert, Zhao Jiyong, Sturhahn Wolfgang, Alp E Ercan, Sage J Timothy
Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA.
J Am Chem Soc. 2005 Aug 17;127(32):11200-1. doi: 10.1021/ja051052x.
We use nuclear resonance vibrational spectroscopy (NRVS) to identify the Fe-NO stretching frequency in the NO adduct of myoglobin (MbNO) and in the related six-coordinate porphyrin Fe(TPP)(1-MeIm)(NO). Frequency shifts observed in MbNO Raman spectra upon isotopic substitution of Fe or the nitrosyl nitrogen confirm and extend the NRVS results. In contrast with previous assignments, the Fe-NO frequency of these six-coordinate complexes lies 70-100 cm-1 lower than in the analogous five-coordinate nitrosyl complexes, indicating a significant weakening of the Fe-NO bond in the presence of a trans imidazole ligand. This result supports proposed mechanisms for NO activation of heme proteins and underscores the value of NRVS as a direct probe of metal reactivity in complex biomolecules.
我们使用核共振振动光谱法(NRVS)来确定肌红蛋白(MbNO)的NO加合物以及相关的六配位卟啉Fe(TPP)(1-MeIm)(NO)中Fe-NO的伸缩频率。在对Fe或亚硝酰氮进行同位素取代时,MbNO拉曼光谱中观察到的频率变化证实并扩展了NRVS的结果。与先前的归属不同,这些六配位配合物的Fe-NO频率比类似的五配位亚硝酰配合物低70-100 cm-1,这表明在存在反式咪唑配体的情况下,Fe-NO键显著减弱。这一结果支持了所提出的血红素蛋白NO活化机制,并强调了NRVS作为复杂生物分子中金属反应性直接探针的价值。