Direct electrochemistry and spectroelectrochemistry of osmium substituted horseradish peroxidase.
In this contribution the substitution of the central protoporphyrin IX iron complex of horseradish peroxidase by the respective osmium porphyrin complex is described. The direct electrochemical reduction of the Os containing horseradish peroxidase (OsHRP) was achieved at ITO and modified glassy carbon electrodes and in combination with spectroscopy revealed the three redox couples Os(III)HRP/Os(IV)HRP, Os(IV)HRP/Os(V)HRP and Os(V)HRP/Os(VI)HRP. The midpoint potentials differ dependent on the electrode material used with E(1/2) (Os(III/IV)) of -0.4 V (ITO) and -0.25 V (GC), E(1/2) (Os(IV)/(V)) of -0.16 V (ITO) and +0.10 V (GC), and E(1/2) (Os(V/VI))of +0.18 V (ITO), respectively. Moreover, with immobilised OsHRP the direct electrocatalytic reduction of hydrogen peroxide and tert-butyl hydroperoxide was observed. In comparison to electrodes modified with native HRP the sensitivity of the OsHRP-electrode for tert-butyl hydroperoxide is higher.
Department of Analytical Biochemistry, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
Noya
N
Loew
Ulla
U
Wollenberger
Frieder W
FW
Scheller
Martin
M
Katterle
D001059:Apoproteins / Q000737:chemistry; D004553:Electric Conductivity; D004563:Electrochemistry; D004566:Electrodes; D006735:Horseradish Peroxidase / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry; D009992:Osmium / Q000737:chemistry*; D010084:Oxidation-Reduction; D011524:Protoporphyrins / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D020122:tert-Butylhydroperoxide / Q000737:chemistry
D001059:Apoproteins; D058085:Iron Compounds; D011524:Protoporphyrins; C515099:dodecacarbonyl iron; D009992:Osmium; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D007501:Iron; D006735:Horseradish Peroxidase; C041104:dimethyl protoporphyrin IX