ࡱ> &(%a jbjb,, "NN2222222h  h,R9222K22FZ222222 a0kk2hh,hh,Abstract - Amanda Shores - SURF 2007 "CO Recombination of Wild Type Cytochrom c Oxidase from Rhodobacter sphaeroides" Cytochrome c oxidase (CcO) plays a key role in the electron transport chain. Its role is to reduce O2 to water with electrons provided by cytochrome c; This redox reaction is coupled to the translocation of four protons across the inner mitochondrial membrane or plasma membrane in the case of bacteria. This creates an electrochemical proton gradient across the membrane, which is used by ATP synthase to make ATP. The enzymes active site can also bind CO, which prevents O2 from binding. It is still unknown what the exact intermediates are upon the binding of CO to, and dissociation of CO from CcO. Bacterial heme-copper oxidases, which have a much simpler structure then the eukaryotic enzyme, have been used as a model to study eukaryotic CcO. In this study, CcO from Rhodobacter spaeroides was isolated. Time-resolved optical absorption following photolysis of CO from the fully reduced enzyme was recorded and analyzed by singular value decomposition and global exponential fitting. The analyses revealed three to four lifetimes. Three life-times showed decay rates of 0.9 ms, 185 ms, 25 ms, whereas four life-times revealed decay rates of 0.8 ms, 85 ms, 810 ms, and 26 ms. The microsecond lifetimes are attributed to conformational changes at the heme a3 site. The millisecond rate is due to the CO recombination at the heme a3. Further experiments are required to identify the exact structures of the individual intermediates. The time-resolved optical absorption difference spectra were the same for aa3 isolated from bacteria grown in baffled flasks as those grown in the unbaffled flasks, indicating similar aeration in both. &wxWX\ ] i j  z |    & ( x z Ŀh'h_H*h'h_OJQJhh_6hWgGh_6 hh_hu[Lh_H*hu[Lh_6 h_H*hs`Eh_H*hbQ3h_6hlh_6!h xh_B*CJOJQJphh_h_>*B*CJphh_)%&wxgd_ 1h/ =!"#$%@@@ [pNormalCJ_HaJmH sH tH DA@D Default Paragraph FontRi@R  Table Normal4 l4a (k@(No List z%&wx0ˀ0ˀ0ˀ0ˀ0ˀ0wx 88 88   ENQX^ijux  hk~lp:@4@ @@ @ @@UnknownGTimes New Roman5Symbol3 ArialC Lucida Grande"qhf۸&f۸&^  !24B3HX)?[pAbstractFreya%PB Sci Admin Computing UC Santa Cruz Oh+'0 , H T `lt|' Abstract.28FreyareyreyNormal&PB Sci Admin Computing UC Santa Cruz2Microsoft Word 11.2@@U(@U(^ ՜.+,0 hp  'UCSC   Abstract Title  !"#$'Root Entry FÙ)1Table WordDocument"SummaryInformation(DocumentSummaryInformation8CompObjXObjectPoolÙÙ FMicrosoft Word DocumentNB6WWord.Document.8