Keil Claudia, Petermann Eva, Oei Shiao Li
Institut für Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany.
Arch Biochem Biophys. 2004 May 1;425(1):115-21. doi: 10.1016/j.abb.2004.02.024.
Phenolic phytochemicals such as tannins, which are natural constituents of green tea, red wine, and other plant products, are considered to have cancer-preventive properties. An important endogenous mediator of tumorigenesis is the nuclear enzyme poly(ADP-ribose) polymerase 1 (PARP-1). PARP-1 synthesizes polymers of ADP-ribose (PAR), which, in turn, are degraded by the catabolic enzyme poly(ADP-ribose) glycohydrolase (PARG). In the present study, we investigated the effects of tannins on the level of PAR in HeLa nuclear extracts. The addition of tannins to nuclear extracts led to a 40-fold elevation of PAR-levels. The observed increased PAR-levels resulted from inhibition of the catalytic activity of PARG. Additionally, the human PARG cDNA was cloned and the recombinant enzyme was overexpressed and isolated. Recombinant PARG was immobilized using an affinity column composed of tannins covalently linked to Sepharose beads. Finally, an interaction between immobilized PARG and endogenous PARP-1 from HeLa cell extracts is demonstrated.
酚类植物化学物质，如作为绿茶、红酒及其他植物产品天然成分的单宁，被认为具有防癌特性。肿瘤发生的一个重要内源性介质是核酶聚（ADP - 核糖）聚合酶1（PARP - 1）。PARP - 1合成ADP - 核糖（PAR）聚合物，而这些聚合物又会被分解代谢酶聚（ADP - 核糖）糖苷水解酶（PARG）降解。在本研究中，我们调查了单宁对HeLa细胞核提取物中PAR水平的影响。向核提取物中添加单宁导致PAR水平升高了40倍。观察到的PAR水平升高是由于PARG催化活性受到抑制。此外，克隆了人PARG cDNA，并对重组酶进行了过表达和分离。使用由与琼脂糖珠共价连接的单宁组成的亲和柱固定重组PARG。最后，证明了固定化PARG与HeLa细胞提取物中的内源性PARP - 1之间存在相互作用。
