Hemoglobin PAHs oxidation

Hemoglobin is another heme-containing protein, which has been shown to be active towards PAH, oxidation in presence of peroxide [420], This protein was also modified via PEG and methyl esterification to obtain a more hydrophobic protein with altered activity and substrate specificity. The modified protein had four times the catalytic efficiency than that of the unmodified protein for pyrene oxidation. Several PAHs were also oxidized including acenaphthene, anthracene, azulene, benzo(a)pyrene, fluoranthene, fluorene, and phenanthrene however, no reaction was observed with chrysene and biphenyl. Modification of hemoglobin with p-nitrophenol and p-aminophenol has also been reported [425], The modification was reported to enhance the substrate affinity up to 30 times. Additionally, the solvent concentration at which the enzyme showed maximum activity was also higher. Both the effects were attributed to the increase in hydrophobicity of the active site. 

Torres, E., and Vazquez-Duhalt, R., Chemical modification of hemoglobin improves biocatalytic oxidation of PAHs (vol 273, pg 820, 2000). Biochemical and Biophysical Research Communications, 2000. 275(2) pp. 713-714. 

Unfortunately, not all PAHs are substrates for peroxidases. A correlation has been found between the ionization potential (IP) of PAHs and the specific activity of manganese peroxidase, lignin peroxidase, hemoglobin, and chloroperoxidase. A threshold value of IP was found for each enzyme. Lignin peroxidase oxidizes PAHs with IP = 7.55 eV [87], while manganese peroxidase oxidizes PAHs with IP... 

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