Diazoluminomelanin: A Synthetic Electron and Nonradiative Transfer Biopolymer

Abstract

The green hemoprotein (GHP) of erythrocytes is a type-b cytochrome with no known function except for the incidental finding of its ferroactivation of phosphoenolpyruvate carboxykinase which is not present in erythrocytes (Chee and Lardy, 1981). We have previously postulated that GHP can transfer superoxide to methemoglobin, converting it to oxyhemoglobin (Kiel et al., 1988). Although no artificial substrate has been available for measuring the electron transfers mediated by GHP, previous data has indicated that the peroxidations putatively mediated by GHP and hemoglobin in erythrocytes can be inhibited by 3-amino-L-tyrosine (Kiel and Erwin., 1986; Kiel et al., 1988). This derivatized tyrosine is an inhibitor of peroxidases (Kiel, 1988) and inhibits the oxidative burst (superoxide and hydrogen peroxide production) of mouse peritoneal macrophages (Lefkowitz et al., 1988). The latter is associated with an electron transport chain containing a type-b cytochrome (Rossi et al., 1986). Furthermore, when lactoperoxidase is reduced by thiol, its binding of tyrosine derivatives becomes significantly enhanced (Pommier and Cahnmann, 1979). Therefore, a potential existed for the development of a tyrosihe-derived substrate that specifically bound to GHP.