Kim Y S, Kim J W, Lee S E, Oh S H
Department of Biochemistry, Yonsei University College of Medicine, Korea.
J Korean Med Sci. 1990 Sep;5(3):127-35. doi: 10.3346/jkms.1990.5.3.127.
Three kinds of apurinic/apyrimidinic (AP) DNA endonuclease, APcI, APcII, APcIII, were purified from rat liver chromatin through 1M KCl extraction, DEAE-trisacryl ion exchange chromatography. Sephadex G-150 gel filtration and AP DNA cellulose affinity chromatography. Activities of the purified APcI, APcII and APcIII were 62.5, 83.3 and 52.0 EU/mg of protein, respectively. Molecular weights of APcI, APcII and APcIII, each consisting of a single polypeptide, were 30,000, 42,000 and 13,000, and isoelectric points of them were 7.2, 6.3 and 6.2, respectively. Three enzymes showed different substrate specificities; APcI acted only on AP DNA, and APcII acted on both AP DNA and UV DNA, while APcIII acted on 3'-methyl-4-monomethylaminoazobenzene (3'-Me MAB) DNA adduct as well as AP DNA and UV DNA. These results indicate that three kinds of AP DNA endonuclease present in rat liver chromatin have structural and functional diversities.
通过1M氯化钾提取、DEAE - 三乙醇胺离子交换色谱、葡聚糖凝胶G - 150凝胶过滤和AP DNA纤维素亲和色谱，从大鼠肝脏染色质中纯化出三种脱嘌呤/脱嘧啶（AP）DNA内切酶，即APcI、APcII、APcIII。纯化后的APcI、APcII和APcIII的活性分别为62.5、83.3和52.0酶活力单位/毫克蛋白质。APcI、APcII和APcIII均由单一多肽组成，其分子量分别为30,000、42,000和13,000，等电点分别为7.2、6.3和6.2。这三种酶表现出不同的底物特异性；APcI仅作用于AP DNA，APcII作用于AP DNA和紫外线（UV）照射后的DNA，而APcIII除作用于AP DNA和UV DNA外，还作用于3'-甲基-4-单甲基氨基偶氮苯（3'-Me MAB）DNA加合物。这些结果表明，大鼠肝脏染色质中存在的三种AP DNA内切酶具有结构和功能多样性。
