ORIGIN OF SPECTRAL SPLITTING IN HEMOPROTEINS

在所有的血红素蛋白中，亚铁血红素的结构和性质 对运输蛋白的功能起着至关重要的作用。不是的 其他假肢群体之间是否存在如此诱人的关系 基团的结构、光谱和功能，也不是这样的 在活动中心的属性和 蛋白质的功能。细胞色素c(Cytc)很小 血红素蛋白参与所有细胞中的电子传递 呼吸。根据定义，亚铁血红素通过以下方式共价连接 C型细胞色素中乙烯基团的缩合。的结构 许多Cyt C是已知的，允许结构/功能关联， 而这些蛋白质长期以来一直被用作研究一般蛋白质的模型 血红素蛋白中的电子转移问题。在这项工作中，我们是 50年来关于凯林的一个悬而未决的问题 1949年报道了一些Fe(II)血红素蛋白的吸收光谱 随着温度的降低，锐化和Q0，0或？-带分裂。在……里面 尽管对血红素蛋白进行了大量研究，但血红素蛋白的起源 光谱的温度依赖性及其意义(如果有的话)， 对电子传递函数的认识还不是很普遍 在血红素蛋白领域工作的人。在文学作品中， 对于分裂的起源，人们提出了各种模型。合而为一 模型中，有两个蛋白质种群，一个在较低的吸收 另一种在更高的波长。这种解释特别是 很受欢迎，因为其他实验表明蛋白质确实有 亚构象。在另一种型号中，有两个电子设备 过渡。这些对应于退化的级别，但在 一个不对称的环境(如血红素口袋)，一个级别是 相对另一个稳定下来了。样本中的所有分子 会有相同的吸收光谱。通过使用荧光 各向异性我们正在辨别这些不同模型中的哪一个是 正确的答案。这些实验是在 RLBL的时间相关仪器。

In all heme proteins the structure and properties of the heme crucially controls the functioning of the transport protein. For no other prosthetic group is there such an enticing relationship between the structure, spectra and function of the group, nor such a well-defined link between the properties of the active center and the function of the protein. Cytochrome c's (cyt c) are small hemoproteins involved in electron transfer in all cells that have respiration. By definition, the hemes are covalently attached by condensation of vinyl groups in c type cytochromes. The structure of many cyt c's are known, allowing for structure/function correlations, and these proteins have long served as models to study the general question of electron transfer in hemoproteins. In this work we are addressing a 50 year old unsolved problem regarding cyt c. Keilin in 1949 reported that the absorption spectra of some Fe(II) heme proteins sharpen and the Q0,0 or ?-band splits as temp erature lo wers. In spite of numerous studies on heme proteins, the origin of the temperature dependence of the spectrum and its significance, if any, to electron transfer functions has not been generally recognized by people working in the area of hemoproteins. In the literature, various models have been proposed for origin of the split. In one model, there are two populations of proteins, one absorbing at lower and the other at higher wavelength. This interpretation is especially popular, since other experiments indicate that proteins do have subconformations. In another model, there are two electronic transitions. These correspond to levels that are degenerate, but in an asymmetric environment (such as the heme pocket), one level is stabilized relative to the other. All molecules within the sample would have the same absorption spectrum. By using fluorescence anisotropy we are discerning which of these various models is the correct one. These experiments are being performed on the time-correlated instrument at the RLBL.