Tatsumi K, Bose K K, Ayres K, Strauss B S
Biochemistry. 1980 Oct 14;19(21):4767-72. doi: 10.1021/bi00562a008.
Neocarzinostatin (NCS) induces repair in a xeroderma pigmentosum lymphoblastoid line deficient in the ability to repair DNA damage induced with (acetoxyacetyl-amino)fluorene. Repair was demonstrated by the induction of repair synthesis and by the disappearance of NCS-induced single-strand breaks and/or alkaline-labile sites in DNA. Estimation of NCS-induced repair patch size, based on the density shift induced in DNA by extensive shear after incubation of treated cells in medium with bromodeoxyuridine or by calculation from the extent of restoration of DNA sedimentation profiles in alkaline sucrose gradients and the amount of repair synthesis measured by the BND cellulose method, indicated that only a few nucleotides were inserted per repaired region. NCS-treated bacteriophage T7 DNA requires incubation with alkaline phosphatase to make it a substrate for DNA polymerase I. NCS-reacted T7 DNA, even after phosphatase treatment, is not a substrate for a DNA polymerase alpha obtained from human lymphoma cells. NCS-treated T7 DNA did serve as a substrate for the DNA polymerase alpha when incubated with an apurinic/apyrimidinic (AP) endonuclease with associated 5'-3'-exonuclease activity. The results suggest that NCS-induced AP sites could be intermediates for the in vivo repair synthesis.
新制癌菌素（NCS）可诱导在修复由（乙酰氧基乙酰 - 氨基）芴诱导的DNA损伤能力缺陷的着色性干皮病淋巴母细胞系中进行修复。通过诱导修复合成以及NCS诱导的DNA单链断裂和/或碱不稳定位点的消失来证明修复。基于在用溴脱氧尿苷处理细胞后在培养基中广泛剪切诱导的DNA密度变化，或通过从碱性蔗糖梯度中DNA沉降图谱的恢复程度以及通过BND纤维素法测量的修复合成量来计算NCS诱导的修复补丁大小，结果表明每个修复区域仅插入了少数几个核苷酸。经NCS处理的噬菌体T7 DNA需要与碱性磷酸酶一起孵育才能使其成为DNA聚合酶I的底物。即使经过磷酸酶处理，NCS反应的T7 DNA也不是从人淋巴瘤细胞获得的DNA聚合酶α的底物。当与具有相关5'-3'-外切核酸酶活性的无嘌呤/无嘧啶（AP）内切核酸酶一起孵育时，经NCS处理的T7 DNA确实作为DNA聚合酶α的底物。结果表明，NCS诱导的AP位点可能是体内修复合成的中间体。
