Professor Harry B. Gray bliver ved Københavns Universitets årsfest d. 20. november promoveret til æresdoktor. I den anledning har Kemisk Forening og Kemisk Institut dagen før arrangeret en forelæsning af Harry B. Gray. Efter forelæsningen bydes der på et glas fadøl.

Onsdag 19. november 2003, kl. 16.00
Auditorium 1, H.C. Ørsted Instituttet, Universitetsparken 5, 2100 København Ø

Harry B. Gray
California Institute of Technology
Pasadena, California 91125, USA

The Currents of Life: Electron Tunneling through Iron and Copper Proteins.
Electron transfers in photosynthesis and respiration commonly occurs between metal-containing cofactors that are separated by large molecular distances, often in the 10-25 angstrom range. Although these cofactors are weakly coupled electronically, the reactions are remarkably rapid and specific. Work in our laboratory has shown that chemical bonds can provide a guidance system for these and other biological electron transfer reactions: the rates of Fe(II) to Ru(III) and Cu(I) to Ru(III) electron tunneling in Ru-modified iron and copper proteins suggest that distant donor-acceptor couplings in folded polypeptides are mediated by a combination of sigma and hydrogen bonds. Extension of this work to include studies of Ru-linker-substrate/cytochrome P450 conjugates has shown that 20-angstrom electron tunneling to the heme center of the enzyme can be controlled by the structure of the linker that couples the Ru(II) photosensitizer to the substrate. To investigate multistep tunneling, often called hopping, we have developed methods to generate amino acid radicals in structurally characterized Re-modified copper proteins. Our work thus far has shown that the reduction potentials of these radicals must be carefully controlled in order to move an electron more than 30 angstroms in milliseconds or less from a donor to an acceptor.