2026-09-23T07:46:00Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/70375 2023-07-11 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Made available in DSpace on 2014-12-15T23:19:00Z (GMT). No. of bitstreams: 1 8721709.pdf: 7766249 bytes, checksum: 5eee5ad815c5641146d939f706d0fe43 (MD5) Previous issue date: 1986 Embargo set by: Seth Robbins for item 70541 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 305 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986. http://hdl.handle.net/2142/70375 (UMI)AAI8721709 Chemistry, Physical Studies on the Photoreduction of Quinone Analogues in Bacterial Photosynthetic Reaction Centers text McComb, James Craig 2014-12-15T23:19:00Z 2014-12-15T23:19:00Z 10000-01-01 1986 1986 The kinetics and thermodynamics of photo-induced electron transfer were studied in photosynthetic reaction centers from Rhodopseudomonas sphaeroides, R-26 mutant, which were chemically depleted of ubiquinone (Q-10) and reconstituted with various quinone analogues. Ubiquinone prenylogues were found to reconstitute both the primary and secondary quinone acceptor function of the protein, with shorter-chained prenylouges giving rise to smaller electron transfer equilibrium constant (= Q$\sb{\rm A}$Q$\sb{\rm B}\sp{-}$/Q$\sb{\rm A}\sp{-}$Q$\sb{\rm B}$), faster post-flash association kinetics (P$\sp{+}$Q$\sb{\rm A}\sp-$ + Q $\rightarrow$ P$\sp{+}$Q$\sb{\rm A}\sp{-}$Q$\sb{\rm B},$ and thermodynamically less stable semiquinones (P$\sp{+}$Q$\sb{\rm A}$Q$\sb{\rm B}\sp{-} \rightarrow$ P$\sp{+}$Q$\sb{\rm A}$ + Q$\sp{-}$). Plastoquinone A, menaquinone-8, and other prenylquinone analogues were found to not restore secondary electron acceptor function. 2,3 dimethyl, 5,6 dimethoxy benzoquinone, however, did restore functional Q$\sb{\rm B}$ activity. Synthetic analogues such as duroquinone or anthraquinone did not restore secondary electron transfer, and high redox potential analogues such as benzoquinone were found to transfer charge out of the protein binding sites and reacted through a mechanism involving the quinone pool. The role of the isoprenoid side chain was analysed in terms of the enthalpy-entropy compensation effect, in which the side chain structure gave rise to cooperative interactions of the protein with the quinone ring structure. Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.