Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Secondary metabolites, especially polyketides are very important for their antibiotic and other pharmaceutical activities. Fungi catalyse a highly diverse array of oxidative rearrangements which result in rapid creation of complex molecular motifs. The development in the field of molecular biology leads to invention of new compounds. Different enzymes were studied which catalyse these biological reactions and their functions were and investigated by targeted gene heterologous expression: TenA, cytochrome p450 enzyme produced by Beauveria bassiana which encodes a 2-Pyridone synthase, it is responsible for the ring expansion step in tenellin biosynthesis which is difficult step in synthetic chemistry. While TropB, TropC and TropH from Talaromyces stipitatus are involved in the biosynthesis of the fungal tropolones which have many biological activities. tropB encodes a FAD-dependent monooxygenase which dearomatises 3- methylorcinaldehyde via hydroxylation at C-3; and tropC encodes a non-heme Fe(II) dependent dioxygenase which catalyses the oxidative ring expansion to the tropolone nucleus via oxidation of the 3-methyl group. TropH is also an aldehyde dehydrogenase was found to be responsible for the dehydrogenation of stipitaldehydic acid. So cloning and expression steps were examined for getting pure and active protein which furtherly exposed to physical characterization and crystallization steps. It helps in determining the biological and functional characteristics

Issued also as CD