Dizdaroglu M, Karahalil B, Sentürker S, Buckley T J, Roldán-Arjona T
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Biochemistry. 1999 Jan 5;38(1):243-6. doi: 10.1021/bi9819071.
A functional human homologue of Escherichia coli endonuclease III (Nth-Eco protein) has recently been cloned and characterized [Aspinwall, R., Rothwell, D. G., Roldan-Arjona, T., Anselmino, C., Ward, C. J., Cheadle, J. P., Sampson, J. R., Lindahl, T., Harris, P. C., and Hickson, I. D. (1997) Proc. Natl. Acad. Sci. U.S.A., 94, 109-114]. This enzyme, designated hNTH1 protein, shares an extensive sequence similarity with Nth-Eco protein and a related enzyme from Schizosaccharomyces pombe (Nth-Spo protein). We investigated the substrate specificity of this human enzyme for oxidative DNA base damage, using the technique of gas chromatography/isotope-dilution mass spectrometry. Four different DNA substrates damaged by various free radical-generating systems were used. 5-Hydroxycytosine, thymine glycol, 5-hydroxy-6-hydrothymine, 5,6-dihydroxycytosine, and 5-hydroxyuracil were substrates of hNTH1 protein among 17 lesions found in DNA substrates. The substrate specificity and excision kinetics of the human enzyme were found to be significantly different from those of Nth-Spo and Nth-Eco proteins.
最近已克隆并鉴定出大肠杆菌核酸内切酶III（Nth-Eco蛋白）的功能性人类同源物[Aspinwall, R., Rothwell, D. G., Roldan-Arjona, T., Anselmino, C., Ward, C. J., Cheadle, J. P., Sampson, J. R., Lindahl, T., Harris, P. C., and Hickson, I. D. (1997) Proc. Natl. Acad. Sci. U.S.A., 94, 109 - 114]。这种酶被命名为hNTH1蛋白，与Nth-Eco蛋白以及来自粟酒裂殖酵母的一种相关酶（Nth-Spo蛋白）具有广泛的序列相似性。我们使用气相色谱/同位素稀释质谱技术研究了这种人类酶对氧化性DNA碱基损伤的底物特异性。使用了四种由各种自由基产生系统损伤的不同DNA底物。在DNA底物中发现的17种损伤中，5-羟基胞嘧啶、胸腺嘧啶乙二醇、5-羟基-6-氢胸腺嘧啶、5,6-二羟基胞嘧啶和5-羟基尿嘧啶是hNTH1蛋白的底物。发现人类酶的底物特异性和切除动力学与Nth-Spo和Nth-Eco蛋白的显著不同。
