Long range intramolecular electron transfer in azurins

The disulfide bridge linking cysteines-3 and -26 in the blue copper aruzin isolated from Alcaligenes faecalis (Alc.faec.) and Pseudomonas fluorescens B (Ps.fluor) reacts with pulse radiolytically produced CO 2 - radical anions to yield the disulfide radical ion, RSSR - . This radical then dacays by an intramolecular electron transfer (et) to the Cu(II) center whith is at a distance of ∼2.6nm. At 25 o C and pH 7.0, the rate constants of the intramolecular electron transfer reactions are 11 ± 2 and 22 ± 3 s -1 in Alc. faec. and Ps. Fluor. azurin, respectively