“…Electron self-exchange reactions of cytochromes c, C551, and by (Gupta et al, 1972;Gupta, 1973;Concar et al, 1986Concar et al, , 1991Dixon et al, 1989Dixon et al, , 1990Timkovich et al, 1988) and copper proteins azurin (Groeneveld & Canters, 1985;Groeneveld et al, 1988; Ugurbil & Mitra, 1984), plastocyanin (Beattie et al, 1975;Armstrong et al, 1985), and amicyanin (Lommen et al, 1988) have been investigated to clarify the influence of structural and/or external factors (pH, ionic strength) on the rates of electron-transfer reactions. In particular, the dependence of self-exchange rate constants k on ionic strength has been the subject of experimental and theoretical studies (van Leeuwen, 1983; Marcus & Sutin, 1985).…”