Langen R, Chang I J, Germanas J P, Richards J H, Winkler J R, Gray H B
Beckman Institute, California Institute of Technology, Pasadena 91125, USA.
Science. 1995 Jun 23;268(5218):1733-5. doi: 10.1126/science.7792598.
Electron coupling through a beta strand has been investigated by measurement of the intramolecular electron-transfer (ET) rates in ruthenium-modified derivatives of the beta barrel blue copper protein Pseudomonas aeruginosa azurin. Surface histidines, introduced on the methionine-121 beta strand by mutagenesis, were modified with a Ru(2,2'-bipyridine)2(imidazole)2+ complex. The Cu+ to Ru3+ rate constants yielded a distance-decay constant of 1.1 per angstrom, a value close to the distance-decay constant of 1.0 per angstrom predicted for electron tunneling through an idealized beta strand. Activationless ET rate constants in combination with a tunneling-pathway analysis of the structures of azurin and cytochrome c confirm that there is a generally efficient network for coupling the internal (native) redox center to the surface of both proteins.
通过测量β桶状蓝铜蛋白铜绿假单胞菌天青蛋白的钌修饰衍生物中的分子内电子转移（ET）速率，研究了通过β链的电子耦合。通过诱变在甲硫氨酸-121β链上引入的表面组氨酸，用Ru(2,2'-联吡啶)2(咪唑)2+络合物进行修饰。从Cu+到Ru3+的速率常数产生了每埃1.1的距离衰减常数，该值接近于通过理想化β链进行电子隧穿预测的每埃1.0的距离衰减常数。无活化能的ET速率常数与天青蛋白和细胞色素c结构的隧穿途径分析相结合，证实存在一个将内部（天然）氧化还原中心与两种蛋白质表面耦合的普遍有效的网络。
