Kozu T, Kurihara T, Seno T
J Biochem. 1981 Feb;89(2):551-61. doi: 10.1093/oxfordjournals.jbchem.a133231.
Three forms of DNA polymerase, named enzymes A, B, and C, that preferred (rA)n x (dT)12-18 as a template-primer, were partially purified from an extract of rat spleen. Enzymes B and C, both sedimenting at 9S, appeared to correspond to DNA polymerase gamma. However, they differed in their behavior on phosphocellulose and DNA-cellulose column chromatographies, and in their optimum KCl and divalent cation requirements for activity. Enzyme A showed a unique property. Like DNA polymerase beta, it sedimented at 3.8S, was resistant to reagents blocking sulfhydryl groups, and was inhibited by phosphate, but it differed from DNA polymerase beta with respect to elution positions from DEAE-cellulose, phosphocellulose and DNA-cellulose columns, Km value (lower by one order of magnitude for dTTP), and template-primer preference. Enzyme A was found in the mitochondrial fraction, in which DNA polymerase beta was not detectable. Enzymes A and C were isolated from the nuclear fraction, but this fraction did not contain enzyme B. The cytosol contained only enzyme A. The mitochondrial fraction contained enzyme A and enzyme C-like polymerase. Enzyme B was obtained with enzymes A and C only by extraction of the whole cell homogenate. Enzyme B may be labile or may be an artificial form of DNA polymerase gamma formed during the purification procedures.
从大鼠脾脏提取物中部分纯化出三种形式的DNA聚合酶，分别命名为酶A、酶B和酶C，它们优先选择（rA）n x（dT）12 - 18作为模板引物。酶B和酶C的沉降系数均为9S，似乎对应于DNA聚合酶γ。然而，它们在磷酸纤维素和DNA纤维素柱色谱上的行为，以及对活性的最佳KCl和二价阳离子需求方面存在差异。酶A表现出独特的性质。它与DNA聚合酶β一样，沉降系数为3.8S，对阻断巯基的试剂有抗性，并受磷酸盐抑制，但在从DEAE - 纤维素、磷酸纤维素和DNA纤维素柱上的洗脱位置、Km值（对dTTP低一个数量级）以及模板引物偏好方面与DNA聚合酶β不同。酶A存在于线粒体部分，在该部分未检测到DNA聚合酶β。酶A和酶C从细胞核部分分离得到，但该部分不含酶B。胞质溶胶中仅含有酶A。线粒体部分含有酶A和类似酶C的聚合酶。仅通过全细胞匀浆提取才能获得与酶A和酶C一起的酶B。酶B可能不稳定，或者可能是纯化过程中形成的DNA聚合酶γ的人工形式。
