Application of 19F NMR spectroscopy to a study of carbon monoxide binding to human hemoglobin modified at Cys-beta 93 with the S-trifluoroethyl residue.
Application of 19F NMR spectroscopy to a study of carbon monoxide binding to human hemoglobin modified at Cys-beta 93 with the S-trifluoroethyl residue.
复制标题
应用 19F NMR 光谱研究一氧化碳与用 S-三氟乙基残基修饰的 Cys-β 93 上的人血红蛋白的结合。
DOI：
10.1016/0003-9861(84)90115-2
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发表时间：
1984
影响因子：
3.9
通讯作者：
Knowles,FC
中科院分区：
文献类型：
--
作者：
Knowles,FC
2,2,2-三氟乙基残基（-SCH2CF3）已被纳入人血红蛋白Hb4(SH)2中，作为Cys-β93的报告基团，使用一系列二硫交换反应[F]。C.诺尔斯（1981）。Biochem.110, 19-26]。羧基血红蛋白（COHb）4(SSCH2CF3)2在235.2 MHz处的19f NMR谱为半峰高50 Hz宽的波段。一氧化碳衍生物向无配体形式的转化伴随着125 Hz （0.53 ppm）的下场位移。将称重等分的Hb4(SSCH2CF3)2和（COHb）4(SSCH2CF3)2溶液混合，得到已知分数饱和的一氧化碳溶液。从19f核磁共振光谱的共振强度的振幅中得出了这些样品的F ā的独立估计。这些独立的测定F ā值的方法并不一致。在六磷酸肌醇存在的情况下，从19f核磁共振谱中得出的F′值比实际值要小得多。两种独立的测定方法之间的差异可以用一氧化碳与α-链结合的优先顺序来解释。通过去除磷酸盐，消除了与α-链结合的偏好。提出了血红蛋白中协同效应传递的模型，该模型解释了血红蛋白-氧解离曲线的特征形状以及19f核磁共振实验显示的链非均质性。
TheS-2,2,2-trifluoroethyl residue (-SCH2CF3) has been incorporated into human hemoglobin, Hb4(SH)2, as a reporter group at Cys-β93 using a sequence of disulfide interchange reactions [F. C. Knowles (1981)Anal. Biochem.110,19–26]. The19F NMR spectrum at 235.2 MHz of carboxyhemoglobin (COHb)4(SSCH2CF3)2was a band 50 Hz wide at half peak height. Conversion of the carbon monoxide derivative to the ligand-free form was accompanied by a downfield shift of 125 Hz (0.53 ppm). Weighed aliquots of solutions of Hb4(SSCH2CF3)2and (COHb)4(SSCH2CF3)2were mixed, yielding solutions of known fractional saturation with carbon monoxide. An independent estimate of F̄ of these samples was derived from the amplitudes of the resonance intensities in the19F NMR spectra. These independent methods for determination of the value of F̄ were not uniformly in agreement. In the presence of inositol hexaphosphate the estimate of F̄ derived from19F NMR spectra was considerably less than the actual value. The discrepancies between the two independent methods for determining F̄ can be explained by a preferred order of binding of carbon monoxide to the α-chains. The preference for binding to the α-chains was abolished by removing phosphates. A model for transmission of cooperative effects in hemoglobin was presented which accounted for the characteristic shape of the hemoglobin-oxygen dissociation curves as well as the chain heterogeneity revealed by19F NMR experiments.