Enzyme-Based Organic Synthesis. Cheanyeh Cheng

Enzyme-Based Organic Synthesis - Cheanyeh Cheng


Скачать книгу
alt="Chemical reaction depicting enantiopure asymmetric microbial Baeyer–Villiger oxidation of rac-bicyclo[3.2.0]hept-2-en-6-one."/>

      2.1.8 Peroxidation Reactions

      In mammalian cells, hydrogen peroxide and organic hydroperoxides are synthesized continuously during aerobic metabolism. Peroxides can damage the cell components by their formation of highly reactive hydroxyl radicals that can initiate lipid peroxidation, to oxidize amino acid side chains in proteins, and to cause DNA strand breaks and base modification [120]. Therefore, peroxides must be detoxified continuously to prevent oxidation of cellular components by peroxides or peroxide‐derived reactive oxygen species (ROS). In addition, the generation of peroxides in cells consumes oxygen, which causes the disposal of peroxides particularly important for human brain because brain cells utilize 20% of the oxygen used by the body [121]. In cells, H2O2 is produced by the disproportionation of superoxide generated through the mitochondrial respiratory chain as a by‐product with superoxide dismutases (SODs). Besides, H2O2 can also be produced by the reactions using oxidases such as monoamine oxidases [122]. Stereospecifically defined organic peroxides are generated in cells through the pathways of prostaglandins and leukotrienes by cyclooxygenases and lipoxygenases. Hydroperoxides are also formed by unspecific oxidation of polyunsaturated fatty acids in membranes by radical‐mediated lipid peroxidation [123].

Chemical reaction depicting enantioselective 2-hydroperoxylation of saturated and unsaturated long-chain fatty acids with crude enzyme of U. pertusa. Chemical reaction depicting peroxidation of linoleic acid with soybean lipoxygenase and subsequent production of its methyl ester. Chemical reaction depicting mn-LO mediated peroxidation of linoleic acid. Chemical reaction depicting kinetic resolution of aryl hydroperoxides by HRP. Chemical reaction depicting enantioselectivities of the selenosubtilisin-catalyzed kinetic resolution of hydroperoxides [137].

      2.2.1 Reduction of Aldehydes and Ketones

      Chiral alcohols are important building blocks and among the most valuable key intermediates for the production of pharmaceuticals


Скачать книгу