OBSERVATION OF A NEW OXYGEN-ISOTOPE-SENSITIVE RAMAN BAND FOR OXYHEMOPROTEINS AND ITS IMPLICATIONS IN HEME POCKET STRUCTURES
OBSERVATION OF A NEW OXYGEN-ISOTOPE-SENSITIVE RAMAN BAND FOR OXYHEMOPROTEINS AND ITS IMPLICATIONS IN HEME POCKET STRUCTURES
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DOI：
10.1021/ja00102a025
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发表时间：
1994-11-16
影响因子：
15
通讯作者：
KITAGAWA, T
中科院分区：
文献类型：
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作者：
HIROTA, S;OGURA, T;KITAGAWA, T
氧合血红蛋白(HBO(2))和细胞色素C氧化酶(CcO2-2)在低于Fe-O-2伸缩模式(Nu(Fe-O2))的频率范围内发现了一个新的氧同位素敏感拉曼光谱。Hb(16)O(2)在425 cm(-1)，Hb(18)O(2)移动到405 cm(-1)，Hb(16)O(18)O(2)移动到423和407 cm(-1)，CCO.O-16(2)对应的带出现在435 cm(-1)，CCO.O-18(2)移动到415 cm(-1)，相应地，该带被指定为Fe-O-O弯曲模式(Delta(FeOO))。氧合肌球蛋白(MBO(2))没有相应的条带。Hb(16)O(2)，Hb(16)O(18)O(2)，Hb(18)O(16)O(2)，Hb(18)O(16)O(2)和Hb(18)O(2)分别在568,567,544和544 cm(-1)处观察到Fe-On伸缩模式(nu(Fe-O2))，MBO(2)在571,569,547和545 cm(-1)处观察到相应的伸缩模式，CCOO-2在571,567,548和544 cm(-1)处观察到相应的模式。HBO(2)和MBO(2)的Nu(Fe-O2)带宽相同，是CoO-2的1.5倍宽，表明后者的Fe-O-O几何构型更接近固定。尽管结合氧在HBO(2)和CoO-2中的反应活性有很大差异，但它们的Nu(Fe-O2)和Delta(FeOO)频率以及O-2-同位素频率位移是相似的，表明Fe-O-O结合几何结构相似。一个孤立的三原子分子的常规坐标计算可以重现观测到的同位素频移，其中MBO(2)的键角为115度，而HBO(2)的键角为155度。
A new oxygen-isotope-sensitive Raman band was found for oxyhemoglobin (HbO(2)) and oxycytochrome c oxidase (CcO.O-2) in the frequency region lower than the Fe-O-2 stretching mode (nu(Fe-O2)). This band was located at 425 cm(-1) for Hb(16)O(2) and shifted to 405 cm(-1) with Hb(18)O(2) and to similar to 423 and similar to 407 cm(-1) with Hb(16)O(18)O. Th, corresponding band appeared at 435 cm(-1) for CCO.O-16(2) and shifted to 415 cm(-1) with CCO.O-18(2), Accordingly, the band has been assigned to the Fe-O-O bending mode (delta(FeOO)) However, the corresponding band could not be identified for oxymyoglobin (MbO(2)). The Fe-On stretching mode (nu(Fe-O2)) was observed at 568, 567, 544, and 544 cm(-1) for Hb(16)O(2), Hb(16)O(18)O(2), Hb(18)O(16)O(2), Hb(18)O(2), respectively, and the corresponding modes were observed at 571, 569, 547, and 545 cm(-1) for MbO(2) and 571, 567, 548, and 544 cm(-1) for CcO.O-2. The nu(Fe-O2) bandwidths of HbO(2) and MbO(2) were alike and 1.5 times broader than that of CcO.O-2, suggesting that the Fe-O-O geometry is more nearly fixed in the latter. Despite the greatly different reactivities of bound O-2 in HbO(2) and CcO.O-2, their nu(Fe-O2) and delta(FeOO) frequencies and O-2-isotopic frequency shifts were alike, indicating similar Fe-O-O binding geometries. Normal coordinate calculations for an isolated three-atom molecule could reproduce the observed isotopic frequency shifts with the 115 degrees bond angle reported for MbO(2), but not with the 155 degrees angle reported for HbO(2).