The Highly Stereoselective Oxidation of Polyunsaturated Fatty Acids by Cytochrome P450BM-3

Abstract

Cytosine deaminase (EC 3.5.4.1), a non-mammalian enzyme, catalyzes the deamination of cytosine and 5-fluorocytosine to form uracil and 5-fluorouracil, respectively. Eukaryotic cells have been genetically modified with a bacterial cytosine deaminase gene to express a functional enzyme. When the genetically modified cells are combined with 5-fluorocytosine, it creates a potent negative selection system, which may have important applications in cancer gene therapy. In this paper, we introduce a novel positive selection method based upon the expression of the cytosine deaminase gene. This method utilizes inhibitors in the pyrimidine de novo synthesis pathway to create a condition in which cells are dependent on the conversion of pyrimidine supplements to uracil by cytosine deaminase. Thus, only cells expressing the cytosine deaminase gene can be rescued in a positive selection medium.

Resolvin E1, an endogenous lipid mediator derived from omega-3 eicosapentaenoic acid, protects against 2,4,6-trinitrobenzene sulfonic acid-induced colitis

“…Acetylation of COX-2 with aspirin treatment promotes the generation of 18R-HEPE, which also may account for some of the bioactivity profile of aspirin. Without aspirin, 18R-HEPE also could be generated by bacterial cytochrome P450 monooxygenase (7,13). Once formed, 18R-HEPE is then further converted by means of cell-cell interactions and the sequential action of the leukocyte lipoxygenase reaction that leads to the formation of 5S,12R,18R-trihydroxy-6Z,8E,10E,14Z,16E-eicosapentaenoic acid (RvE1) (8).…”

Engineering the substrate specificity of Bacillus megaterium cytochrome P-450 BM3: hydroxylation of alkyl trimethylammonium compounds

“…The measured k cat for palmitate, 81 s −" , is somewhat greater than that for the C #! unsaturated fatty acid arachidonate (53 s −" ; [11]) ; these are the fastest catalytic rates yet reported for P-450 mono-oxygenase reactions.…”

“…14581, the structure of whose haem domain was reported by Ravichandran et al [3], is of particular interest as a soluble model for the membrane-bound mammalian enzymes. P-450 BM3 (CYP102) catalyses hydroxylation (in the ωk1, ωk2 and ωk3 positions) and\or epoxidation of medium-and long-chain fatty acids [7][8][9][10][11]. It contains a P-450 haem domain and an NADPH-cytochrome P-450 reductase flavoprotein domain in a single polypeptide chain (M r 118 000), both of which show clear sequence homology with the corresponding mammalian proteins [12].…”

Regioselective Biocatalytic Hydroxylation of Fatty Acids by Cytochrome P450s

“…For unsaturated fatty acids from C 12 to C 22 , usually both, in-chain hydroxylation and epoxidation at the C=C-bond closest to the terminus were found (Fig. 3) [101][102][103]. The high activity for unsaturated fatty acids and branched fatty acids led to speculations whether these compounds constitute its natural (Tables 6, 7) [104,105].…”