EPR spectroscopy of oxygen-tolerant [NiFe]-hydrogenases [Elektronische Ressource] / vorgelegt von Miguel Florian Saggu

EPR spectroscopy of oxygen-tolerant[NiFe]-hydrogenasesvorgelegt vonDiplom-ChemikerMiguelFlorianSagguaus SchwerteVon der Fakultät II - Mathematik und Naturwissenschaftender Technischen Universität Berlinzur Erlangung des akademischen GradesDoktor der Naturwissenschaften- Dr. rer. nat. -genehmigte DissertationPromotionsausschuss:Vorsitzender: Prof. Dr. Thomas FriedrichBerichter: Prof. Dr. Peter HildebrandtBerichter: Prof. Dr. Robert BittlTag der wissenschaftlichen Aussprache: 09. Dezember 2009Berlin 2010D 83AbstractHydrogenases are metalloenzymes and play a pivotal role in the energy metabolism of a varietyof microorganisms. They catalyze the reversible cleavage of molecular hydrogen into two protonsand two electrons. However, one drawback is their catalytic inactivation upon exposure to oxy-gen. [FeFe]-hydrogenases are irreversibly inactivated by oxygen, whereas [NiFe]-hydrogenasesusually are reversibly inactivated to the so-called ’ready’ and ’unready’ states. Only a few [NiFe]-hydrogenases show a remarkable oxygen-tolerance, e.g. the [NiFe]-hydrogenases from the ’Knall-gasbacterium’ Ralstonia eutropha H16 investigated in this work. Re H16 harbors three different[NiFe]-hydrogenases, all of them being able to oxidize molecular hydrogen under ambient oxygenconcentrations.