Rux J J, Dawson J H
Department of Chemistry, University of South Carolina, Columbia 29208.
FEBS Lett. 1991 Sep 23;290(1-2):49-51. doi: 10.1016/0014-5793(91)81222-t.
Horse heart cytochrome c with either histidine or cysteine replacing the endogenous axial methionine ligand at position 80 has been characterized with magnetic circular dichroism (MCD) spectroscopy in the UV-visible region. Comparison of the MCD spectra of the mutant proteins in the ferric state to those of authentic bis-imidazole- and imidazole/thiolate-ligated ferric heme proteins clearly shows that the histidine-imidazole and cysteine-thiolate groups of the replacement amino acids at position 80 are coordinated to the heme iron in the mutant proteins. This study demonstrates the power of MCD spectroscopy in identifying axial ligands in mutant heme proteins. Accurate axial ligand assignment is essential for proper interpretation of the altered properties of such novel proteins.
在紫外-可见区域，通过磁圆二色光谱（MCD）对马心细胞色素c进行了表征，该细胞色素c在80位上的内源性轴向甲硫氨酸配体分别被组氨酸或半胱氨酸取代。将突变蛋白处于高铁状态下的MCD光谱与真正的双咪唑和咪唑/硫醇盐配位的高铁血红素蛋白的光谱进行比较，结果清楚地表明，80位取代氨基酸的组氨酸-咪唑和半胱氨酸-硫醇盐基团与突变蛋白中的血红素铁配位。这项研究证明了MCD光谱在鉴定突变血红素蛋白轴向配体方面的作用。准确的轴向配体归属对于正确解释此类新型蛋白质的改变特性至关重要。
