The Role of Molecular Crowding in Long-Range Metalloprotein Electron Transfer: Dissection into Site- and Scaffold-Specific Contributions

ZITARE, ULISES A.; ESPINOZA-CARA, ANDRÉS; VILA, ALEJANDRO J.; SZUSTER, JONATHAN; LEGUTO, ALCIDES J.; DANIEL H. MURGIDA; SCOCOZZA, MAGALI F.; MORGADA, MARCOS N.

Buenos Aires

Encuentro; Shaping the Future of German-Argentinian Scientific Cooperation ? The Role of CuriosityDriven Research; 2018

Fundación Alexander Von Humboldt

Here is reported the effect of molecular crowding on long-range protein electron transfer (ET) and disentangle the specific responses of the redox site and the protein milieu. To this end, we studied two different one-electron redox proteins that share the cupredoxin fold but differ in the metal centre, T1 mononuclear blue copper and binuclear CuA, as well as chimeras with hybrid properties by incorporating different T1 centres within the CuA scaffold or by swapping loops between orthologous proteins from different organisms to perturb the CuA site1. The heterogeneous ET kinetics of the different proteins was studied by protein film electrochemistry at variable electronic couplings and with two different crowding agents. The results reveal a strong frictional control of the ET. The effect is ascribed to the dynamical coupling of the metal site and the milieu, which for T1 is found to be twice stronger than for CuA, and the activation energy of protein-solvent motion that is dictated by the overall scaffold.