MICR 4180 Final: Exam Review.docx
1 Mar 2015
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Document Summary
It is believed that higher pahs: hydroxylation occurs in all cases, except: may naphthalene dioxygenase, benzene dioxygenase and biphenyl these enzymes also attack the (phenanthrene, anthracene). right next to an adjacent r group. Typified by catechol 2,3 dioxygenase, protocatechuate 2,3 dioxygenase and protocatechuate 4,5 dioxygenase. *produces 2 keto 4 hydroxyvalerate as the key. A. 1 ring hydroxylating dioxygenases: group 1 has 4 subunits eg. toluene, biphenyl and naphthalene dioxygenases, group 2 has 3 subunits eg. benzoate and benzene sulfonate dioxygenases, group 3 has 2 subunits eg. phthalate dioxygenase. The number of nadph required varies with the substrate. Pcp-4-monooxygenase hydroxylates at the para position; less specific in terms of substituents, however, the presence of an ortho halogen substituent in the substrate is a pre-requisite. Ring hydroxylating dehydrogenase which forms cis-ring diol, then dihydroxylating to restore aromaticity of ring and formation of hydroxy derivate then set compound up for ring cleavage: intra-diol cleavage and going through beta-keto pathway.
