Rhodobacter capsulatus ın CBB3-tipi sitokrom oksidaz enzimininde kısmi olarak korunmuş üç aminoasit mutasyonunun karakterizasyonu

Heme-Copper Oxygen reductases are responsible for catalyzing the reduction of oxygen to water and generate an electrochemical gradient, which is used for ATP synthesis. cbb3-type oxidases are the most distinct members of the HCOs which are characterized by high catalytic activity at low oxygen concentrations and reduced proton pumping. Analyses on genomic sequences for C-type oxygen reductase family and mutagenesis studies on conserved residues showed that each of these conserved residues has a critical role in structure and/or function of the enzyme. In this study, three partially conserved residues Aspargine 265, Tyrosine 420 and Phenylalanine 480, which are unique to C-type oxygen reductase family, were substituted to Valine, Phenylalanine and Alanine respectively by site directed mutagenesisfor the investigation ofthe diversity, mechanism and structure of this highly diverse family. Characterization of the mutants from Rhodobacter capsulatuswas done with respect to their effects on activity, assembly and proton pumping stoichiometry.Mutations at the position of N265 and Y420 showed that, they have critical role on the enzyme activity and assembly while F480 has role in function,proton translocation.Findings support the assumption that partially conserved residues may also have important role in the structure and/or function of thecbb3-type oxidases.