【作者】 卢景雰； Bender,C.J.； McCracken.J.C.； Peisach,J.； Sevens.J.C.； McMillin.D.R.；

【Author】 Lu Jingfen Bender,C.J. McCracken,J.C. Peisach,J. Severns,J.C. McMillan,D.R. National Laboratory of Natural & Biomimetic Drugs,Beijing medical Univ.,Beijing 100083

【机构】 北京医科大学天然药物及仿生药物国家重点实验室； 爱因斯坦医学院分子药理系； 密西根大学化学系； 普渡大学化学系；

【摘要】 本文用脉冲EPR波谱学的核调制效应研究漆酶的汞衍生物(NDL)中Ⅱ型铜的结合位点的特性。样品中Ⅰ型铜被Hg(Ⅱ)取代。比较MDL及一系列铜--咪唑和铜--二甲基咪唑模型化合物的三脉冲自旋回波的实验数据,并通过对回波衰减包络线的计算机模拟及富利埃交换.可以清楚地看到二个组氨酸咪唑和Cu(Ⅱ)赤道配位。在许多含Ⅱ型铜的氧化酶中,Cu(Ⅱ)和咪唑形成配合物。离金属离子中心较远处14K的核四极矩参数和2--甲基咪唑的相似。但是在MDL中则不同,它的核四极矩参数和咪唑的相同。从富利埃变换波谱上得到低频区主要的频率成分如下:在MDL中为0.74,1.51 MHz;在铜咪唑化合物中为0.56-0.78,1.46 MHz;而在铜--二甲基咪唑化合物中则为0.53,1.07,1.60 MHz.所以在Ⅱ型铜漆酶的研究中,用铜--咪唑化物作模型更为合适。更多还原

【Abstract】 The nuclear modulation effect in pulsed EPR spectroscopy was used to study the type 2 copper binding site in the mercury derivative of laccase（MDL） where the type 1 copper was substituted by Hg（Ⅱ）.By comparing 3-pulse spin echo data for MDL with a series of mode compounds and carrying out computer simulations of echo decay envelope as well as Fourier transform,it is suggested that two histidyl imidazoles are equatorially coordinating to Cu（Ⅱ）.Unlike a number of oxidases containing type 2 copper where the nuclear quadrupole parameters for the remote ¹⁴N of Cu（Ⅱ） coordinated imidazole resemble those of 2- methylimidazole,the patameters for MDL duplicate those of imidazole.The fundamental frequencies in low frequency regine from Fourier Transform are as following:0.74,1.51 MHz for MDL and 0.56-O.78,1.46 MHz for Cu-imidazole complex,while 0.53,1.07,1.60 MHz for Cu-2-methylimidazole complex.It is proved that the Cu（Ⅱ）-imidazole model complexes are more suitable for the study of the type 2 copper binding sites in MDL than the Cu（Ⅱ）-2-methylimidazole model complexes as the magmetic models.更多还原