Polyethylene glycol-modified hemin having peroxidase activity in organic solvents

Hemin, having two carboxyl groups, was coupled with monomethoxypolyethylene glycol, PEG, through the ester bond formed with carbodiimide. The PEG-modified hemin was readily soluble not only in neutral aqueous solution but also in organic solvents. Its absorption spectrum in 1,1,1-trichloroethane showed a sharp Soret band at 398 nm. The modified hemin catalyzed the peroxidase-reaction in organic solvent and in aqueous solution using hydrogen peroxide or peroxidized linolenic acid as hydrogen acceptor and o-phenylene diamine as hydrogen donor. The activity of PEG-hemin in 1,1,1-trichloroethane was greater than that in an aqueous solution; k1 values in 1,1,1-trichloroethane were 2.3 X 10(3) M-1 sec-1 with hydrogen peroxide and 7.0 X 10(2) M-1 sec-1 with peroxidized linolenic acid, and the value in an aqueous solution was 3.0 X 10 M-1 sec-1 with hydrogen peroxide.