Prodöhl Alexander, Dreher Carolin, Hielscher Ruth, Hellwig Petra, Schneider Dirk
Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany.
Protein Expr Purif. 2007 Dec;56(2):279-85. doi: 10.1016/j.pep.2007.08.007. Epub 2007 Aug 24.
Folding and assembly studies with alpha-helical membrane proteins are often hampered by the absence of high-level expression systems as well as by missing suitable in vitro refolding procedures. Experimental constraints and requirements for heterologous expression and in vitro assembly of cytochrome b6 have been examined and conditions for in vitro reconstitutions of the protein have been optimized. Cytochrome b6 can serve as an excellent model system for in vitro studies on the dynamic interplay of an apo-protein and heme cofactors during assembly of a transmembrane b-type cytochrome. In vitro assembled cytochrome b6 binds two hemes with different midpoint potentials and both ferri as well as ferro heme bind to the apo-cytochrome. However, the ferro cytochrome appears to be less stable than the ferri form.
α-螺旋膜蛋白的折叠和组装研究常常受到缺乏高水平表达系统以及缺少合适的体外重折叠程序的阻碍。已对细胞色素b6的异源表达和体外组装的实验限制及要求进行了研究，并优化了该蛋白的体外重组条件。细胞色素b6可作为一个出色的模型系统，用于体外研究跨膜b型细胞色素组装过程中脱辅基蛋白与血红素辅因子之间的动态相互作用。体外组装的细胞色素b6结合两个具有不同中点电位的血红素，高铁血红素和亚铁血红素均可与脱辅基细胞色素结合。然而，亚铁细胞色素似乎不如高铁形式稳定。
