Employing laser flash-quench triggering methods, we have shown that 20-angstrom, coupling-limited Cu(I) to Ru(III) electron tunneling in Ru-modified blue copper proteins can occur on the microsecond timescale both in solutions and crystals. Redox equivalents can be transferred even longer distances by multistep tunneling, often called hopping, through intervening amino acid side chains. The lessons we have learned about the control of electron tunneling and hopping through biological molecules are now guiding the construction of wired and sensitizer-modified P450s for investigations of electrocatalysis and photocatalysis of oxygenation reactions.