Editing Polychlorinated biphenyl (section)

===Species dependent===
Metabolism is also dependent on the species of organism; different organisms have slightly different P450 enzymes that metabolize certain PCBs better than others. Looking at the PCB metabolism in the liver of four sea turtle species (green, [[olive ridley]], loggerhead and hawksbill), green and hawksbill sea turtles have noticeably higher [[hydroxylation]] rates of PCB 52 than olive ridley or loggerhead sea turtles. This is because the green and hawksbill sea turtles have higher P450 2-like protein expression. This protein adds three hydroxyl groups to PCB 52, making it more polar and water-soluble. P450 3-like protein expression that is thought to be linked to PCB 77 metabolism, something that was not measured in this study.<ref name="pubs.acs.org"/>