Contributions to catalysis and potential interactions of the three catalytic domains in a contiguous trimeric creatine kinase.
Contributions to catalysis and potential interactions of the three catalytic domains in a contiguous trimeric creatine kinase.
复制标题
对连续三聚肌酸激酶中三个催化结构域的催化作用和潜在相互作用的贡献。
DOI：
10.1111/j.1742-4658.2007.06226.x
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Ellington,WRoss
中科院分区：
文献类型：
--
作者：
Hoffman,GreggG;Davulcu,Omar;Sona,Sona;Ellington,WRoss
三个独立的肌酸激酶（CK）亚型家族存在于动物中。其中两种（细胞质和线粒体）是专性寡聚体。第三，鞭毛，是单体，但含有三个完整的CK域的残基。 目前尚不清楚每个相邻鞭毛结构域中的活性位点是否具有催化活性，如果是，它们是否能够独立发挥作用。在这里，我们利用定点诱变来选择性地禁用单个活性位点及其所有可能的组合。动力学研究表明，这些突变对底物结合和协同作用的影响最小。有趣的是，活性位点不是催化等价的，并且实际上是相互依赖的，这是以前仅在低聚CK亚型中报道的现象。
Three separate creatine kinase (CK) isoform families exist in animals. Two of these (cytoplasmic and mitochondrial) are obligate oligomers. A third, flagellar, is monomeric but contains the residues for three complete CK domains. It is not known whether the active sites in each of the contiguous flagellar domains are catalytically competent, and, if so, whether they are capable of acting independently. Here we have utilized site‐directed mutagenesis to selectively disable individual active sites and all possible combinations thereof. Kinetic studies showed that these mutations had minimal impact on substrate binding and synergism. Interestingly, the active sites were not catalytically equivalent, and were in fact interdependent, a phenomenon that has previously been reported only in the oligomeric CK isoforms.