Electron movement through proteins and DNA.

Nature utilizes the phenomenon of single electron transfer very widely, especially in metallo-proteins. In systems when the metal donor (D) is well separated from the acceptor (A) by polypeptide chains, the transferring electron is presumed to be bonded, in part, by these chains, which may influence the pathway taken. This situation can be probed by radiolytic injection of electrons into proteins at low temperatures. One aim of this brief review is to consider how information derived from such radiolysis studies, and followed by ESR spectroscopy, may possibly impinge on studies of D-A systems. Electrons can also be injected into duplex DNA in this way, and the results are compared with those for proteins. They are also considered in the light of recent studies of D-A electron-transfer via a polynucleotide strand. It seems that such transfers are very efficient, and it is tentatively suggested that Nature may also use this conductivity in some as yet undiscovered systems.