Dam R J, Kongslie K F, Griffith O H
Biophys J. 1974 Dec;14(12):933-9. doi: 10.1016/S0006-3495(74)85960-6.
Hemoglobin is examined as a model system for intrinsic photoelectron labeling experiments. The absolute photoelectron quantum yields of hemin, hemoglobin, and apohemoglobin thin films were measured in the 180-230 nm wavelength region. Hemin exhibits a quantum yield of approximately 6 x 10(-4) electrons per incident photon at 180 nm, 9 x 10(-5) electrons per incident photon at 210 nm, and 2 x 10(-6) electrons per incident photon at 230 nm. At all wavelengths the hemin curve lies approximately a factor of 20 above that of hemoglobin and two orders of magnitude above that of apohemoglobin. High image contrast is observed between hemin and apohemoglobin in low magnification photoelectron micrographs, suggesting the feasibility of intrinsic labeling studies involving heme proteins. The quantum yield of hemoglobin is discussed in terms of linear contributions from heme groups and protein weighted by their relative surface areas. The fractional surface areas based on the known structure of hemoglobin are consistent with values derived from the quantum yields of hemin and apohemoglobin.
血红蛋白作为本征光电子标记实验的一个模型体系进行了研究。在180 - 230 nm波长范围内测量了血红素、血红蛋白和脱辅基血红蛋白薄膜的绝对光电子量子产率。血红素在180 nm处的量子产率约为每入射光子6×10⁻⁴个电子，在210 nm处为每入射光子9×10⁻⁵个电子，在230 nm处为每入射光子2×10⁻⁶个电子。在所有波长下，血红素的曲线都比血红蛋白的曲线高约20倍，比脱辅基血红蛋白的曲线高两个数量级。在低倍光电子显微镜照片中观察到血红素和脱辅基血红蛋白之间有高图像对比度，这表明涉及血红素蛋白的本征标记研究是可行的。根据血红素基团和蛋白质按其相对表面积加权的线性贡献来讨论血红蛋白的量子产率。基于血红蛋白已知结构的分数表面积与从血红素和脱辅基血红蛋白的量子产率得出的值一致。
