作者:Elżbieta Dąbrowska-Maś、Tomasz Frączyk、Tomasz Ruman、Karolina Radziszewska、Piotr Wilk、Joanna Cieśla、Zbigniew Zieliński、Agata Jurkiewicz、Barbara Gołos、Patrycja Wińska、Elżbieta Wałajtys-Rode、Andrzej Leś、Joanna Nizioł、Adam Jarmuła、Piotr Stefanowicz、Zbigniew Szewczuk、Wojciech Rode
DOI:10.1039/c1ob06360j
日期:——
Highly purified preparations of thymidylate synthase, isolated from calf thymus, and L1210 parental and FdUrd-resistant cells, were found to be nitrated, as indicated by a specific reaction with anti-nitro-tyrosine antibodies, suggesting this modification to appear endogenously in normal and tumor tissues. Each human, mouse and Ceanorhabditis elegans recombinant TS preparation, incubated in vitro in the presence of NaHCO3, NaNO2 and H2O2 at pH 7.5, underwent tyrosine nitration, leading to a Vmaxapp 2-fold lower following nitration of 1 (with human or C. elegans TS) or 2 (with mouse TS) tyrosine residues per monomer. Enzyme interactions with dUMP, meTHF or 5-fluoro-dUMP were not distinctly influenced. Nitration under the same conditions of model tripeptides of a general formula H2N-Gly-X-Gly-COOH (X = Phe, Tyr, Trp, Lys, Arg, His, Ser, Thr, Cys, Gly), monitored by NMR spectroscopy, showed formation of nitro-species only for H-Gly-Tyr-Gly-OH and H-Gly-Phe-Gly-OH peptides, the chemical shifts for nitrated H-Gly-Tyr-Gly-OH peptide being in a very good agreement with the strongest peak found in 15N-1H HMBC spectrum of nitrated protein. MS analysis of nitrated human and C. elegansproteins revealed several thymidylate synthase-derived peptides containing nitro-tyrosine (at positions 33, 65, 135, 213, 230, 258 and 301 in the human enzyme) and oxidized cysteine (human protein Cys210, with catalytically critical Cys195 remaining apparently unmodified) residues.
高度纯化的胸苷酸合酶制备物,分离自小牛胸腺,以及L1210亲代细胞和FdUrd抗性细胞,被发现被硝基化,这是由与抗硝基酪氨酸抗体的特定反应所表明的,表明这种修饰在正常和肿瘤组织中内源性地出现。每个人类、小鼠和秀丽隐杆线虫的重组TS制备物,在体外pH 7.5条件下与NaHCO3、NaNO2和H2O2共孵育,经历了酪氨酸硝基化,导致每单体硝基化1(人类或秀丽隐杆线虫TS)或2(小鼠TS)个酪氨酸残基后,表观最大反应速度Vmaxapp降低2倍。酶与dUMP、meTHF或5-氟尿嘧啶-dUMP的相互作用没有明显受到影响。在相同条件下硝基化模型三肽,其一般公式为H2N-Gly-X-Gly-COOH(X = Phe, Tyr, Trp, Lys, Arg, His, Ser, Thr, Cys, Gly),通过NMR光谱监测,显示只有H-Gly-Tyr-Gly-OH和H-Gly-Phe-Gly-OH肽形成硝基物种,硝基化的H-Gly-Tyr-Gly-OH肽的化学位移与15N-1H HMBC光谱中发现的最高峰非常吻合。硝基化的人类和秀丽隐杆线虫蛋白质的MS分析揭示了几个胸苷酸合酶衍生肽,含有硝基酪氨酸(在人类酶中的位置33、65、135、213、230、258和301)和氧化半胱氨酸(人类蛋白质Cys210,具有催化关键的Cys195显然未被修饰)残基。