Mössbauer and EPR spectroscopy on protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa

摘要: Abstract Protocatechuate 3,4-dioxygenase (EC 1.13.11.3) from Pseudomonas aeruginosa has been investigated by EPR and Mossbauer spectroscopy. Low temperature data on the native enzyme ( Fe 3+ , S = 5 2 ) yields a hyperfine field Hsat −525 kG at nucleus. This observation is inconsistent with earlier suggestions, based data, of rubredoxin-like ligand environment around iron, i.e. tetrahedral sulfur coordination. Likewise, dithionite-reduced parameters unlike those reduced rubredoxin. We conclude that iron atoms are in previously unrecognized environment. The ternary complex 3,4-dihydroxyphenylpropionate O2 signals g 6.7 5.3; these result an excited state Kramers doublet. kinetics disappearance parallels product formation decay as observed optical spectrum. establish to be high-spin ferric characterized large negative zero-field splitting, D ⋍ −2 cm −1 .