Replacing Electron Transport Cofactors with Hydrogenases

Handle URI:
http://hdl.handle.net/10754/621950
Title:
Replacing Electron Transport Cofactors with Hydrogenases
Authors:
Laamarti, Rkia ( 0000-0002-6559-9734 )
Abstract:
Enzymes have found applications in a broad range of industrial production processes. While high catalytic activity, selectivity and mild reaction conditions are attractive advantages of the biocatalysts, particularly costs arising from required cofactors pose a sever limitation. While cofactor-recycling systems are available, their use implies constraints for process set-up and conditions, which are a particular problem e.g. for solid-gas-phase reactions. Several oxidoreductases are able to directly exchange electrons with electrodes. Hence, the co-immobilization of both, an electron-utilizing and an electron-generating oxidoreductase on conductive nanoparticles should facilitate the direct electron flow from an enzymatic oxidation to a reduction reaction circumventing redox-cofactors requirements. In such a set-up, hydrogenases could generate and provide electrons directly form gaseous hydrogen. This thesis describes the co-immobilization of the oxygen tolerant hydrogenases from C. eutropha or C. metallidurans and cytochrome P450BM3 as test system. Conductive material in the form of carbon nanotubes (CNT) serves as a suitable support. A combination of the hydrogenase and the catalytic domain of P450BM3 immobilized on carbon nanotubes were tested for the oxidation of lauric acid in the presence of hydrogen instead of an electron-transport cofactor. The GC-MS analysis reveals the conversion of 4% of lauric acid (LA) into three products, which correspond to the hydroxylated lauric acid in three different positions with a total turnover (TON) of 34. The product distribution is similar to that obtained when using the wildtype P450BM3 with the nicotinamide adenine dinucleotide phosphate (NADPH) cofactor. Such electronic coupling couldn’t be achieved for the conversion of other substrates such as propane and cyclohexane, probably due to the high uncoupling rate within the heme-domain of cytochrome P450BM3 when unnatural substrates are introduced.
Advisors:
Eppinger, Jorg ( 0000-0001-7886-7059 )
Committee Member:
Takanabe, Kazuhiro ( 0000-0001-5374-9451 ) ; Arold, Stefan T. ( 0000-0001-5278-0668 ) ; Lenz, Oliver
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Bioscience
Issue Date:
Dec-2016
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorEppinger, Jorgen
dc.contributor.authorLaamarti, Rkiaen
dc.date.accessioned2016-12-06T11:18:10Z-
dc.date.available2016-12-06T11:18:10Z-
dc.date.issued2016-12-
dc.identifier.urihttp://hdl.handle.net/10754/621950-
dc.description.abstractEnzymes have found applications in a broad range of industrial production processes. While high catalytic activity, selectivity and mild reaction conditions are attractive advantages of the biocatalysts, particularly costs arising from required cofactors pose a sever limitation. While cofactor-recycling systems are available, their use implies constraints for process set-up and conditions, which are a particular problem e.g. for solid-gas-phase reactions. Several oxidoreductases are able to directly exchange electrons with electrodes. Hence, the co-immobilization of both, an electron-utilizing and an electron-generating oxidoreductase on conductive nanoparticles should facilitate the direct electron flow from an enzymatic oxidation to a reduction reaction circumventing redox-cofactors requirements. In such a set-up, hydrogenases could generate and provide electrons directly form gaseous hydrogen. This thesis describes the co-immobilization of the oxygen tolerant hydrogenases from C. eutropha or C. metallidurans and cytochrome P450BM3 as test system. Conductive material in the form of carbon nanotubes (CNT) serves as a suitable support. A combination of the hydrogenase and the catalytic domain of P450BM3 immobilized on carbon nanotubes were tested for the oxidation of lauric acid in the presence of hydrogen instead of an electron-transport cofactor. The GC-MS analysis reveals the conversion of 4% of lauric acid (LA) into three products, which correspond to the hydroxylated lauric acid in three different positions with a total turnover (TON) of 34. The product distribution is similar to that obtained when using the wildtype P450BM3 with the nicotinamide adenine dinucleotide phosphate (NADPH) cofactor. Such electronic coupling couldn’t be achieved for the conversion of other substrates such as propane and cyclohexane, probably due to the high uncoupling rate within the heme-domain of cytochrome P450BM3 when unnatural substrates are introduced.en
dc.language.isoenen
dc.subjectBiocatalysisen
dc.subjectCytochrome P450BM3en
dc.subjectHydrogeansesen
dc.subjectelectronic couplingen
dc.subjectcofactor free systemen
dc.titleReplacing Electron Transport Cofactors with Hydrogenasesen
dc.typeDissertationen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberTakanabe, Kazuhiroen
dc.contributor.committeememberArold, Stefan T.en
dc.contributor.committeememberLenz, Oliveren
thesis.degree.disciplineBioscienceen
thesis.degree.nameDoctor of Philosophyen
dc.person.id113391en
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