Velichko I S, Baykov A A
Belozersky Institute of Physico-Chemical Biology and School of Chemistry, Lomonosov Moscow State University, Russia.
Biochemistry (Mosc). 1997 Mar;62(3):233-6.
The inorganic pyrophosphatase of Escherichia coli is a tightly hexamer of identical subunits. Upon interaction of its two mutant forms in which the trimer-trimer contacts were weakened because of E20D and H136Q substitutions, a hybrid hexameric E20D/H136Q-PPase is formed. The catalytic activity of its constituent H136Q trimer is same of its hexamer, whereas metal-binding affinity is significantly decreased. These results point to an interdependence of two trimers in catalysis by hexameric pyrophosphatase.
大肠杆菌的无机焦磷酸酶是由相同亚基紧密结合形成的六聚体。在其两种突变形式相互作用时，由于E20D和H136Q取代导致三聚体-三聚体接触减弱，形成了杂合六聚体E20D/H136Q-焦磷酸酶。其组成部分H136Q三聚体的催化活性与其六聚体相同，而金属结合亲和力显著降低。这些结果表明六聚体焦磷酸酶催化过程中两个三聚体之间存在相互依赖性。
