The role of the electron spin in chemistry and biology
has received much attention recently owing to to the possible electromagnetic
field effects on living organisms and the prospect of using molecules
in the emerging field of spintronics. Recently the chiral-induced
spin selectivity effect was observed by electron transmission through
organic molecules. In the present study, we demonstrated the ability
to control the spin filtering of electrons by light transmitted through
purple membranes containing bacteriorhodopsin (bR) and its D96N mutant.
The spin-dependent electrochemical cyclic voltammetry (CV) and chronoamperometric
measurements were performed with the membranes deposited on nickel
substrates. High spin-dependent electron transmission through the
membranes was observed; however, after the samples were illuminated
by 532 nm light, the spin filtering in the D96N mutant was dramatically
reduced whereas the light did not have any effect on the wild-type
bR. Beyond demonstrating spin-dependent electron transmission, this
work also provides an interesting insight into the relationship between
the structure of proteins and spin filtering by conducting electrons