IRON CARBONYL BOND GEOMETRIES OF CARBOXYMYOGLOBIN AND CARBOXYHEMOGLOBIN IN SOLUTION DETERMINED BY PICOSECOND TIME-RESOLVED INFRARED-SPECTROSCOPY
IRON CARBONYL BOND GEOMETRIES OF CARBOXYMYOGLOBIN AND CARBOXYHEMOGLOBIN IN SOLUTION DETERMINED BY PICOSECOND TIME-RESOLVED INFRARED-SPECTROSCOPY
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DOI：
10.1073/pnas.85.14.5062
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发表时间：
1988-07-01
影响因子：
11.1
通讯作者：
HOCHSTRASSER, RM
中科院分区：
文献类型：
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作者：
MOORE, JN;HANSEN, PA;HOCHSTRASSER, RM
用皮秒时间分辨红外光谱研究了碳氧肌红蛋白（MbCO）和碳氧血红蛋白（HbCO）在室温溶液中的铁羰基几何构型。偏振红外和可见光光束被用来监测的变化，在红外吸收的绑定CO伸缩带的配体的光解。光解和红外探测光束的垂直和平行相对偏振的吸光度变化的比率与配体键轴和血红素平面的法线之间的角度直接相关。比率，因此，角度，已获得的配置产生的主要CO伸缩红外吸收带的HbCO和MbCO：18度的1951 cm-1频带的HbCO，20度和35度，分别为1944 cm-1和1933 cm-1频带的MbCO。MbCO和HbCO的结构与本文报道的X射线衍射和皮秒实验一致，其中Fe-C键向血红素法线倾斜，Fe-C-O角与180度显着不同。
The iron-carbonyl geometries in carboxymyoglobin (MbCO) and carboxyhemoglobin (HbCO) in ambient temperature solution have been investigated using picosecond time-resolved infrared spectroscopy. Polarized infrared and visible beams were used to monitor the change in infrared absorbance of the bound CO stretch bands on photodissociation of the ligand. The ratio of the change in absorbance for perpendicular and parallel relative polarizations of the photolysis and infrared probe beams is directly related to the angle between the ligand bond axis and the normal to the heme plane. Ratios, and hence the angles, have been obtained for the configurations giving rise to the principal CO stretch infrared absorption bands of HbCO and MbCO: 18 degrees for the 1951 cm-1 band of HbCO; 20 degrees and 35 degrees, respectively, for the 1944 cm-1 and 1933 cm-1 bands of MbCO. Structures consistent with x-ray diffraction and the picosecond experiments reported here are proposed for MbCO and HbCO in which the Fe-C bond tilts to the heme normal and the Fe-C-O angle differs significantly from 180 degrees.