Fritz-Wolf K, Schnyder T, Wallimann T, Kabsch W
Max-Planck-Institut für medizinische Forschung, Abteilung Biophysik, Heidelberg, Germany.
Nature. 1996 May 23;381(6580):341-5. doi: 10.1038/381341a0.
Creatine kinase (CK, EC 2.7.3.2), an enzyme important for energy metabolism in cells of high and fluctuating energy requirements, catalyses the reversible transfer of a phosphoryl goup from phosphocreatine to ADP. We have solved the structure of the octameric mitochondrial isoform, Mib-CK, which is located in the intermembrane compartment and along the cristae membranes. Mib-CK consumes ATP produced in the mitochondria for the production of phosphocreatine, which is then exported into the cytosol for fast regeneration of ATP by the cytosolic CK isoforms. The octamer has 422 point-group symmetry, and appears as a cube of side length 93 angstrom with a channel 20 angstrom wide extending along the four-fold axis. Positively charged amino acids at the four-fold faces of the octamer possibly interact with negatively charged mitochondrial membranes. Each monomer consists of a small alpha-helical domain and a large domain containing an eight-stranded antiparallel beta-sheet flanked by seven alpha-helices. The conserved residues of the CK family form a compact cluster that covers the active site between the domains.
肌酸激酶（CK，EC 2.7.3.2）是一种对能量需求高且波动的细胞中的能量代谢很重要的酶，它催化磷酸基团从磷酸肌酸可逆地转移到ADP。我们解析了八聚体线粒体同工型Mib-CK的结构，它位于膜间隙和嵴膜上。Mib-CK消耗线粒体中产生的ATP来生成磷酸肌酸，然后磷酸肌酸被输出到胞质溶胶中，由胞质CK同工型快速再生ATP。八聚体具有422点群对称性，呈边长为93埃的立方体，有一条20埃宽的通道沿四重轴延伸。八聚体四重面上带正电荷的氨基酸可能与带负电荷的线粒体膜相互作用。每个单体由一个小的α螺旋结构域和一个大结构域组成，大结构域包含一个由七个α螺旋侧翼的八链反平行β折叠片层。CK家族的保守残基形成一个紧密的簇，覆盖结构域之间的活性位点。
