BIOL354 Lecture Notes - Lecture 7: Biotransformation, Environmental Toxicology, Xenobiotic
14 Jun 2020
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Document Summary
Biotransformation of organics: an enzyme-mediated metabolic processes may alter xenobiotic compounds, once subject to biotransformation solubility, generally increases. But may increase or decrease toxicity: metabolism of lipophilic toxicants can be considered as two stages. Phase ii reactions: process of biotransformation of organics from the parent chemical into another chemical occurs via metabolic enzymes. Major site of biotransformation is liver: eg. hepatocytes. Increase the hydrophilicity of contaminants by addition reactive functional groups: eg. -cooh, -oh, -nh2, -sh. Predominately oxidation reactions but include hydrolysis, hydration & reduction reactions. Most phase i enzymes are cytochrome p450 (cyp) enzymes, aka. mixed function oxygenases/oxidases mfos: metabolite may be less toxic or more toxic eg. organophosphate insecticides toxic oxon derivative, generally or ideally less toxic. Cytochrome p450: enzyme superfamily of more than 50, with a haemprotein, consist of. Two dehydrogenases nadph cytochrome p450 reductase & nadh cytochrome b5 reductase. Two hemoproteins cytochrome p450 & cytochrome b5.
