衰老过程中大白鼠脾细胞DNA聚合酶催化DNA合成的忠实性研究

Changes of Rat spleen Cell DNA Polymerases Catalizing DNA Synthesis During Aging: A fidelity study

从大鼠脾细胞提取DNA聚合酶,经DEAE纤维素分离可分为DNA聚合酶α及β,DNA聚合酶的活性与衰老无关,而DNA聚合酶α催化DNA合成的忠实性在衰老过程中明显降低,当DNA合成的反应体系中缺失三种脱氧核苷酸时,断乳鼠、青年鼠及老年鼠脾细胞DNA聚合酶α的活性分别相当于4种脱氧核苷酸均存在时的4.0％,7.6％及13.9％。DNA聚合酶α催化DNA合成的忠实性还受二价阳离子的影响,当以M■^(++)代替Mg^(++)时,其忠实性降低。DNA聚合酶β催化DNA合成的忠实性与衰老无关。

DNA polymerases ware extracted from rat spleen cells with 0. 4M potassium phosphate buffer and seperated into α and β fractions through DEAE cellulose chromatography. The DNA polymerase activities had no relation with rat ages. The accuracy of DNA synthesis catalyzed by DNA polymerase α and β wasemeasurde at the absence of three unlabled deoxyribonucleotides(dNTPs). It was showed that the fidelity of DNA polymerase α was declined during aging, while DNA polymerase β remained relatively unchanged.