Moranelli F, Lieberman M W
Proc Natl Acad Sci U S A. 1980 Jun;77(6):3201-5. doi: 10.1073/pnas.77.6.3201.
Using a filter binding assay, we have detected and partially purified a protein from human placenta that has a high affinity for N-acetoxy-2-acetylaminofluorene-modified double-stranded DNA (AAF-[3H]DNA) of bacteriophage T7. This protein has been partially purified from a 1 M NaCl extract of a crude nuclear fraction by a combination of ion-exchange and nucleic acid affinity chromatography. With AAF-[3H]DNA as the substrate, the binding reaction reached equlibrium within 1 hr at 4 degrees C, and the extent of binding ws proportional to the amount of protein added. Complex formation was dependent on both pH and salt concentration and was unaffected by the presence of sulfhydryl-blocking agents. The purest protein fraction also recognizes DNA modified with methylmethane-sulfonate or methylnitrosourea. It shows little or no recognition of single-stranded DNA, double-stranded DNA, supercoiled bacteriophage phiX174 DNA, partially depurinated DNA, glucosylated bacteriophage T4DNA, or UV-irradiated DNA. No endo- or exonuclease activity, DNA polymerase activity, or glucosylase activity for AAF-DNA was detectable in the preparation.
我们使用滤膜结合试验,从人胎盘中检测并部分纯化了一种蛋白质,该蛋白质对噬菌体T7的N-乙酰氧基-2-乙酰氨基芴修饰的双链DNA(AAF-[3H]DNA)具有高亲和力。通过离子交换和核酸亲和色谱相结合的方法,已从粗核级分的1 M NaCl提取物中部分纯化了该蛋白质。以AAF-[3H]DNA为底物,结合反应在4℃下1小时内达到平衡,结合程度与添加的蛋白质量成正比。复合物的形成取决于pH值和盐浓度,不受巯基封闭剂的影响。最纯的蛋白质组分也能识别经甲基磺酸甲酯或甲基亚硝基脲修饰的DNA。它对单链DNA、双链DNA、超螺旋噬菌体phiX174 DNA、部分脱嘌呤的DNA、糖基化噬菌体T4 DNA或紫外线照射的DNA几乎没有或没有识别能力。在制备物中未检测到针对AAF-DNA的内切或外切核酸酶活性、DNA聚合酶活性或糖基化酶活性。