Kumble K D, Kornberg A
Department of Biochemistry, Beckman Center, Stanford University School of Medicine, Stanford, California 94305-5307, USA.
J Biol Chem. 1996 Oct 25;271(43):27146-51. doi: 10.1074/jbc.271.43.27146.
Whereas exopolyphosphatases have been purified from yeast and a variety of bacteria, this is the first report characterizing endopolyphosphatases that act on long chain inorganic polyphosphate (polyP). The activity from Saccharomyces cerevisiae, localized in vacuoles, has been purified to homogeneity from a strain that possesses vacuolar proteases. The endopolyphosphatase is a dimer of 35-kDa subunits. Distributive action on polyP750 produces shorter chains to a limit of about polyP60, as well as the more abundant release of polyP3; the Km for polyP750 is 185 nM. Endopolyphosphatases have been identified in a wide variety of sources, except for most eubacteria tested. The activity has been partially purified from rat and bovine brain where its abundance is about 10 times higher than in other tissues but less than 1/10 that of yeast; the limit product of digestion of the partially purified brain enzyme is polyP3.
虽然已从酵母和多种细菌中纯化出胞外多聚磷酸酶，但这是首次报道对长链无机多聚磷酸盐（多聚P）起作用的胞内多聚磷酸酶的特性。来自酿酒酵母且定位于液泡中的活性物质，已从一株具有液泡蛋白酶的菌株中纯化至同质。该胞内多聚磷酸酶是由35 kDa亚基组成的二聚体。对多聚P750的分布作用产生较短的链，直至约多聚P60的极限，以及更大量的多聚P3释放；多聚P750的Km为185 nM。除了大多数测试的真细菌外，已在多种来源中鉴定出胞内多聚磷酸酶。该活性已从大鼠和牛脑中部分纯化，其丰度比其他组织高约10倍，但不到酵母的1/10；部分纯化的脑酶消化的极限产物是多聚P3。
