Poon R, Beerman T A, Goldberg I H
Biochemistry. 1977 Feb 8;16(3):486-93. doi: 10.1021/bi00622a023.
The antitumor protein antibiotic neocarzinostatin causes strand scission of DNA in vitro in the presence of a sulfhydryl compound. The breaks are single stranded in nature and bear 5'-phosphoryl termini. All four deoxymononucleotides are recoverable at the 5'-ends of the cleavage sites although a higher proportion of dGMP and TMP are consistently found. The lesions are not repairable with polynucleotide ligase from Escherichia coli. A quantitative assay was developed to determine the pH profile and time course of the reaction. Data from protection experiments with synthetic and natural DNAs indicate the requirement for thymidylic acid and deoxyadenylic acid in the DNA for cutting. In DNA-RNA hybrids, riboadenylic acid can substitute for deoxyadenylic acid, whereas ribouridylic acid cannot substitute for thymidylic acid. Release of thymine is detected, and the amount of release correlates well with the number of strand scissions.
抗肿瘤蛋白抗生素新制癌菌素在巯基化合物存在的情况下，可在体外引起DNA链断裂。这些断裂本质上是单链的，且带有5'-磷酸末端。尽管始终发现dGMP和TMP的比例较高，但在切割位点的5'-末端可以回收所有四种脱氧单核苷酸。这些损伤不能用来自大肠杆菌的多核苷酸连接酶修复。开发了一种定量测定方法来确定反应的pH曲线和时间进程。来自合成DNA和天然DNA的保护实验数据表明，切割DNA时需要胸苷酸和脱氧腺苷酸。在DNA-RNA杂交体中，核糖腺苷酸可以替代脱氧腺苷酸，而核糖尿苷酸不能替代胸苷酸。检测到胸腺嘧啶的释放，释放量与链断裂的数量密切相关。
