Har-Vardi I, Mali R, Breietman M, Sonin Y, Albotiano S, Levitas E, Potashnik G, Priel E
IVF unit, Department of Obstetrics and Gynaecology, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva 84105, Israel.
Hum Reprod. 2007 Aug;22(8):2183-9. doi: 10.1093/humrep/dem170.
The condensed state of the human sperm's chromatin is essential for the compact structure of the spermatozoon head, which is important for the fertilization process. The enzymes DNA topoisomerases (topo I and topo II) are responsible for the topological structure of the chromatin in somatic cells. The activities and the characterization of topoisomerases in mature human sperm cells have not been previously investigated.
Sperm cells were purified from the semen of healthy donors by standard procedures and assays measuring the activities, protein size and sensitivity to inhibitors of topoisomerases were performed.
Topo I and topo II DNA relaxation activities are present in nuclear extracts derived from human sperm. The sperm topo I activity is inhibited by camptothecin, similarly to the somatic enzyme. An 85 kDa sperm protein, compared with the 100 kDa somatic topo IB enzyme, reacted with anti-human topo I antibody. Sperm topo II lacks the DNA decatenation activity of the somatic enzyme and a 97 kDa protein, compared with the 170 kDa somatic topo IIalpha enzyme, was detected with anti-human topo II antibody. Sperm nuclear extracts contained inhibitors of somatic topo II decatenation activity.
Topoisomerase I and II activities as well as topo I and topo II proteins are present in mature human sperm cells. These enzymes possess unique properties compared with their somatic counterparts.
人类精子染色质的凝聚状态对于精子头部的紧凑结构至关重要，而精子头部结构对于受精过程很重要。DNA拓扑异构酶（拓扑异构酶I和拓扑异构酶II）负责体细胞中染色质的拓扑结构。成熟人类精子细胞中拓扑异构酶的活性和特性此前尚未被研究过。
通过标准程序从健康供体的精液中纯化精子细胞，并进行测量拓扑异构酶活性、蛋白质大小及对抑制剂敏感性的检测。
人类精子来源的核提取物中存在拓扑异构酶I和拓扑异构酶II的DNA松弛活性。与体细胞酶类似，喜树碱可抑制精子拓扑异构酶I的活性。与100 kDa的体细胞拓扑异构酶IB相比，一种85 kDa的精子蛋白与抗人类拓扑异构酶I抗体发生反应。精子拓扑异构酶II缺乏体细胞酶的DNA解连环活性，与170 kDa的体细胞拓扑异构酶IIα相比，用抗人类拓扑异构酶II抗体检测到一种97 kDa的蛋白。精子核提取物中含有体细胞拓扑异构酶II解连环活性的抑制剂。
成熟人类精子细胞中存在拓扑异构酶I和II的活性以及拓扑异构酶I和II蛋白。与体细胞中的对应酶相比，这些酶具有独特的特性。
Zotero 插件