Open AccessMössbauer Studies on the Active Fe …[2Fe‐2S] Site of Putidamonooxin, Its Electron Transport and Dioxygen Activation Mechanism
Author(s) -
BILL Eckhard,
BERNHARDT FrithjofHans,
TRAUTWEIN Alfred Xaver
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb06426.x
Subject(s) - chemistry , cofactor , monooxygenase , oxidoreductase , ferredoxin , substrate (aquarium) , active site , stereochemistry , inorganic chemistry , photochemistry , crystallography , enzyme , cytochrome p450 , biochemistry , oceanography , geology
Putidamonooxin, the oxygenase of a 4‐methoxybenzoate monooxygenase enzyme system, catalyzes the oxidative O‐demethylation of the substrate 4‐methoxybenzoate in conjunction with the NADH: putidamonooxin oxidoreductase. Putidamonooxin is a conjugated iron‐sulfur protein which needs iron ions as cofactors for its enzymatic activity. Putiamonooxin was isolated from Pseudornonus putida , which was grown on a 57 Fe‐enriched culture medium. Thus putidamonooxin was enriched in vivo with 57 Fe up to about 80%. During our Mössbauer study of putidamonooxin a number of parameters have been varied: (a) the oxidation state of putidamonooxin (oxidized, reduced and aerobically reoxidized); (b) the substrate bound to putidamonooxin (Cmethoxybenzoate, benzoate, 4‐ tert ‐butylbenzoate); (c) the temperature between 2.7 K and 245 K; (d) the applied magnetic field between 0 and 0.1 T and (e) the amount of iron cofactor. From our Mössbauer results it is obvious that the iron‐sulfur centers of putidamonooxin are [2 Fe‐2 S] clusters similar to those of the plant‐type ferredoxins. Further, we have evidence for the existence of iron ions (one per [2 Fe‐2S] cluster), which serve as cofactors for the dioxygen activation, functioning as the dioxygen binding site and mediating the electron flow from the [2 Fe‐2 S] cluster to dioxygen.