Characteristics in tyrosine coordinations of four hemoglobins M probed by resonance Raman spectroscopy.
Characteristics in tyrosine coordinations of four hemoglobins M probed by resonance Raman spectroscopy.
复制标题
共振拉曼光谱探测四种血红蛋白 M 的酪氨酸配位特征。
DOI：
10.1021/bi00432a012
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
T. Kitagawa
中科院分区：
文献类型：
--
作者：
M. Nagai;Y. Yoneyama;T. Kitagawa
四种血红蛋白M与酪氨酸配体的共振拉曼光谱，即Hb M萨斯卡通（β远端His-Tyr），Hb M Hyde Park（β近端His-Tyr），Hb M Boston（α远端His-Tyr）和Hb M Iwate（α近端His-Tyr），为阐明萨斯卡通血红蛋白M异常亚基与其它血红蛋白M相比明显易还原的结构起源，对10种血红蛋白M进行了研究。所有的血红蛋白M表现出指纹带的铁-酪氨酸蛋白约1600，1500，和1270 cm-1。然而，血红蛋白M萨斯卡通有最低的铁-酪氨酸伸缩频率，是唯一一个显示的拉曼光谱模式的六坐标血红素异常β亚基，其他显示的模式的五坐标血红素。血红蛋白M萨斯卡通在600 nm处的吸收强度表明中点pH值为5.2的过渡，而血红蛋白M波士顿的吸收强度与pH值从7.2到4.8无关。血红蛋白M萨斯卡通在pH 5.0时酪氨酸配位的指纹带以及铁-酪氨酸伸缩带消失，所得的拉曼光谱与高铁血红蛋白A相似，而血红蛋白M波士顿在pH 5.0时和两个血红蛋白M在pH 10.0时清楚地观察到这些带。这些观察结果表明，血红蛋白M萨斯卡通的异常β链中的血红素的不寻常的特征是由弱的Fe-酪氨酸键导致的，其允许近端组氨酸的弱配位，从而在pH 7下产生六配位高自旋状态。（250字处删节）
Resonance Raman spectra of four hemoglobins (Hbs) M with tyrosinate ligand, that is, Hb M Saskatoon (beta distal His----Tyr), Hb M Hyde Park (beta proximal His----Tyr), Hb M Boston (alpha distal His----Tyr), and Hb M Iwate (alpha proximal His----Tyr), were investigated in order to elucidate structural origins for distinctly facile reducibility of the abnormal subunit of Hb M Saskatoon in comparison with other Hbs M. All of the Hbs M exhibited the fingerprint bands for the Fe-tyrosinate proteins around 1600, 1500, and 1270 cm-1. However, Hb M Saskatoon had the lowest Fe-tyrosinate stretching frequency and was the only one to display the Raman spectral pattern of a six-coordinate heme for the abnormal beta subunit; the others displayed the patterns of a five-coordinate heme. The absorption intensity of Hb M Saskatoon at 600 nm indicated a transition with a midpoint pH at 5.2, whereas that of Hb M Boston was independent of pH from 7.2 to 4.8. The fingerprint bands for the tyrosinate coordination as well as the Fe-tyrosinate stretching band disappeared for Hb M Saskatoon at pH 5.0, and the resultant Raman spectrum resembled that of metHb A, while those bands were clearly observed for Hb M Boston at pH 5.0 and for two Hbs M at pH 10.0. These observations suggest that the unusual characteristics of the heme in the abnormal beta chain of Hb M Saskatoon result from the weak Fe-tyrosinate bond, which allows weak coordination of the proximal histidine, giving rise to the six-coordinate high-spin state at pH 7.(ABSTRACT TRUNCATED AT 250 WORDS)