HIGH AND LOW-RESOLUTION THEORIES OF PROTEIN ELECTRON-TRANSFER

Protein-mediated electronic interactions facilitate biological electro n transfer (ET) reactions, Theory and experiment are being used extens ively to establish atomic-scale descriptions of these reactions, The l ast 20 years have seen a progression of descriptions ranging from squa re barrier protein approximations to tunneling Pathway models, and rec ently to valence orbital Hamiltonian methods. Pathway connectivity, re flecting a protein's secondary and tertiary motif, is predicted (and w as recently confirmed) to determine the ET rate, A critical challenge now is to extract from more detailed orbital descriptions, with millio ns of interaction elements between orbitals, predictions of how primar y sequence and folding-induced contacts influence electron transfer ra tes, Electron transfer contact maps reduce the orbital interaction inf ormation in a manner that allows ready interpretation in the context o f protein motifs and mutations, We discuss these modern models for pro tein ET and the reduced views that are being derived from them.