生物有机大分子中血红素铁的可见光谱特性

Visible Spectral Character of Heme Iron in Biomacromolecules

在实验的基础上 ,对单体血红素、血红蛋白、细胞色素C、过氧化物酶等的可见光吸收光谱进行了比较与分析。生物有机大分子中血红素铁的第五、第六个配位键影响了该有机大分子的可见光谱的特性 ,使吸收峰的形状、位置发生变化。血红素b中铁的第六个配位键的形成使二价铁血红素在红光区有二个吸收峰 ,此时铁原子处于低自旋 ,相对较稳定 ;而在无第六个配位键的高自旋二价铁状态下 ,血红素在红光区表现出只有一个大吸收峰 ,分子处于活泼态。铁第五、第六配位键的状况对含血红素有机物吸收光谱的影响主要是通过改变铁在卟啉环平面上的空间位置和自旋状态等 ,从而改变整个血红素的电子状态所致。血红素的这些光谱特征有利于对含血红素生物有机分子的性质、功能。

The visible spectra of hemin, hemoglobin, cytochrome C, peroxidase and so on were compared and analyzed based on the experiments. The fifth and sixth coordinate bond of heme iron in biomacromolecule may affect their visible spectra in peak form and position. The sixth coordinate bond of ferrous heme iron that is in low-spin displays two peaks, and in high-spin, ferrous heme without the sixth coordinate bond of iron gives only one peak. That is in favor of our understanding of the character, function and stability of heme-containing biomacromolecule. The spectral character of iron coordinate bonds is due to that these coordinate bonds change the iron position related to porphyrin plane and its spin state.