Tang D
Nucleic Acids Res. 1978 Aug;5(8):2861-75. doi: 10.1093/nar/5.8.2861.
A DNA nicking-closing enzyme has been purified from the nuclei of mouse L cells to 90% homogeneity. The denatured and reduced form of the enzyme has a molecular weight of 68,000 which is in agreement with the molecular weight of the native enzyme as determined by gel filtration and by sucrose sedimentation velocity assuming the protein is globular. Therefore, the active form of the enzyme is a monopolypeptide. Its isoelectric point is pH 4.2 +/- 0.2. The nicking-closing activity does not require a cofactor and does not involve any sulfhydryl group. The enzyme requires 0.2 M NaCl and pH in the range of 6.5-7.5 for optimal activity.
一种DNA切口封闭酶已从小鼠L细胞核中纯化出来，纯度达90%。该酶的变性和还原形式分子量为68,000，这与通过凝胶过滤和蔗糖沉降速度测定的天然酶分子量一致（假设该蛋白质为球状）。因此，该酶的活性形式是一种单肽。其等电点为pH 4.2±0.2。切口封闭活性不需要辅因子，也不涉及任何巯基。该酶最佳活性需要0.2M NaCl和pH值在6.5 - 7.5范围内。
