title: The reaction of ferrous leghemoglobin with hydrogen peroxide to form leghemoglobin(IV).
abstract: Ferrous leghemoglobin reacts with hydrogen peroxide to form the stable product, leghemoglobin(IV). The reaction follows second order kinetics (k = 2.24 X 10(4) M-1 S-1 at 20 degrees C) and may be regarded as a single-step, two-electron oxidation. Ferric leghemoglobin is not an intermediate. The oxidation state of leghemoglobin(IV) is established by reductive titration with dithionite; 2 eq of dithionite are required to convert 1 mol of leghemoglobin(IV) to ferrous leghemoglobin. An outstanding property of leghemoglobin(IV) is its stability, little change is noted after 12 h at 25 degrees C. Leghemoglobin(IV) differs from the higher oxidation states of other hemoglobins and myoglobins in that it does not react with hydrogen peroxide to form the oxygenated protein.
mesh_terms: D004227:Dithionite; D006420:Hemeproteins; D006861:Hydrogen Peroxide; D007501:Iron; D007700:Kinetics; D007874:Leghemoglobin; D013053:Spectrophotometry
chemical_list: D006420:Hemeproteins; D007874:Leghemoglobin; D004227:Dithionite; D006861:Hydrogen Peroxide; D007501:Iron