Avaeva S M, Rodina E V, Vorobyeva N N, Kurilova S A, Nazarova T I, Sklyankina V A, Oganessyan V Y, Harutyunyan E H
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119899, Russia.
Biochemistry (Mosc). 1998 May;63(5):592-9.
The three-dimensional structures of E. coli inorganic pyrophosphatase (PPase) and its complexes with Mn2+ in a high affinity site and with Mg2+ in high and low affinity sites determined by authors in 1994-1996 at 1.9-2.2 A resolution are compared. Metal ion binding initiates the shifts of alpha-carbon atoms and of functional groups and rearrangement of non-covalent interaction system of hexameric enzyme molecule. As a result, the apoPPase with six equal subunits turns after Mg2+ binding into the structure with three types of subunits distinguished by structure and occupance of the low affinity Mg2+ site. Induced asymmetry reflects the subunit interactions and cooperativity between Mg2+ binding sites. These molecular rearrangements are structural basis to account for special features of the enzyme behavior and to propose one of the pathways for enzymatic activity regulation of constitutive PPases in vivo.
比较了作者于1994年至1996年测定的大肠杆菌无机焦磷酸酶（PPase）及其在高亲和力位点与Mn2+以及在高、低亲和力位点与Mg2+形成的复合物的三维结构，分辨率为1.9 - 2.2 Å。金属离子结合引发了α-碳原子和官能团的位移以及六聚体酶分子非共价相互作用系统的重排。结果，具有六个相等亚基的脱辅基PPase在结合Mg2+后转变为具有三种亚基类型的结构，这三种亚基类型通过低亲和力Mg2+位点的结构和占据情况来区分。诱导的不对称反映了亚基相互作用以及Mg2+结合位点之间的协同性。这些分子重排是解释该酶行为特殊特征并提出体内组成型PPases酶活性调节途径之一的结构基础。
