Heli Hossein, Amani Mojtaba, Moosavi-Movahedi Ali Akbar, Jabbari Ali, Floris Giovanni, Mura Anna
Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
Biosci Biotechnol Biochem. 2008 Jan;72(1):29-36. doi: 10.1271/bbb.70299. Epub 2008 Jan 7.
The electrochemical behavior of redox centers in the active site of amine oxidases from lentil seedlings and Euphorbia characias latex was investigated using a mercury film electrode. Tyrosine-derived 6-hydroxydopa quinone (TPQ) and copper ions in the active site are redox centers of these amine oxidases. The enzymes undergo two reduction processes at negative potentials related to the reduction of the TPQ cofactor to the corresponding hydroquinones and the reduction of copper ions, (Cu(II)-->Cu(I)). Copper depleted enzymes, prepared by reduction with dithionite followed by dialysis against cyanide, undergo only one reduction process. Nyquist diagrams, recorded at potentials corresponding to the reduction of cofactors as dc-offset, represent charge transfer impedance followed by a Warburg-type line at low frequencies, indicating the occurrence of a diffusion controlled process in the rate-limiting step of the reduction process.
使用汞膜电极研究了扁豆幼苗和大戟乳胶中胺氧化酶活性位点氧化还原中心的电化学行为。酪氨酸衍生的6-羟基多巴醌（TPQ）和活性位点中的铜离子是这些胺氧化酶的氧化还原中心。这些酶在与TPQ辅因子还原为相应的氢醌以及铜离子还原（Cu（II）→Cu（I））相关的负电位下经历两个还原过程。用连二亚硫酸盐还原然后用氰化物透析制备的铜耗尽酶仅经历一个还原过程。在对应于辅因子还原的电位下记录的奈奎斯特图作为直流偏移，表示电荷转移阻抗，随后在低频处出现Warburg型线，表明在还原过程的限速步骤中发生了扩散控制过程。
