Kellogg Jason A, Bren Kara L
Department of Chemistry, College of Arts and Science, University of Rochester, Rochester, NY 14627-0216, USA.
Biochim Biophys Acta. 2002 Dec 16;1601(2):215-21. doi: 10.1016/s1570-9639(02)00471-5.
Cytochromes c are characterized by the presence of a protoporphyrin IX group covalently attached to the polypeptide via one or two thioether bonds to Cys side chains. The heme attachment process, known as cytochrome c maturation, occurs posttranslationally in the periplasm (for bacterial cytochromes c) or in the mitochondrial intermembrane space (for eukaryotic cytochromes c) through a pathway dependent on the organism. It is demonstrated in this work that a mitochondrial cytochrome c expressed in Escherichia coli that undergoes maturation under control of the E. coli cytochrome c maturation factors achieves a native-like structure and stability. The recombinant protein is characterized spectroscopically (by circular dichroism (CD), absorption, and nuclear magnetic resonance (NMR) spectroscopy) and it is verified that the heme and its environment are indistinguishable from authentic horse cytochrome c. Mass spectrometry reveals that the recombinant protein is not acetylated at the N terminus, however, no significant effect on protein structure or stability is detected as a result.
细胞色素c的特征是存在一个原卟啉IX基团，该基团通过与半胱氨酸侧链的一个或两个硫醚键与多肽共价连接。血红素附着过程，即细胞色素c成熟过程，在周质（对于细菌细胞色素c）或线粒体膜间隙（对于真核细胞色素c）中翻译后发生，具体途径取决于生物体。这项工作表明，在大肠杆菌中表达的线粒体细胞色素c在大肠杆菌细胞色素c成熟因子的控制下进行成熟，可获得类似天然的结构和稳定性。通过光谱学方法（圆二色性（CD）、吸收光谱和核磁共振（NMR）光谱）对重组蛋白进行了表征，并证实血红素及其环境与天然马细胞色素c无法区分。质谱分析表明，重组蛋白在N端没有乙酰化，然而，未检测到这对蛋白质结构或稳定性有显著影响。
