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Long-range electron transfer in [Co(diAMsar)-modified cytochrome c derivatives
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MODELS FOR PHOTOINDUCED ELECTRON TRANSFER: SYNTHESIS AND OPTICAL PROPERTIES OF QUINONE SUBSTITUTED, PHENYL LINKED PORPHYRIN DIMERS AND TRIMERS. Yigcent J,. CapMartin R. Johnson and Jonathan L. Sessler, Department of' Chemistry, University of Texas, Austin, Texas 78712 USA.
The synthesis of several quinone substituted, phenyl linked porphyrin dimers and trimers will be described. The well-defined interporphyrin configurations make these compounds suitable models for the study of multistep photoinduced electron transfer. This poster will present synthetic details associated with the preparation of these materials and results of optical analyses carried out with these new model systems.
6043
LONG-RANGE ELECTRON TRANSFER IN [CO(DIAMSAR)]-MODIFIED CYTOCHROME C DERIVATIVES. D. W. Conrad and R. A. Scott, Departments of Chemistry and Biochemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA. We have developed a carbodiimide-based procedure that results in covalent attachment of [Co(diAMsar)13+ complexes to surface glutamate or aspartate residues of horse cytochrome c. Seven singly modified derivatives have been prepared and characterized in terms of the distance between the attached cobalt cage complex and the heme. These distances range from -10 - 20 A. The rates of intramolecular electron transfer from Co(II) to heme Fe(II1) have been measured by flash photolysis using Ru(bpy)a*+ as photosensitizer. The distance dependence of this intramolecular electron transfer rate will be discussed and these results will be compared to other studies of long-range biological electron transfer.
G.044
SEMISYNTHETIC ANALOGS OF CYTOCHROME C: CHANGES AT RESIDUE 67. M. M. Frauenhoff and R. A. Scott, Departments of Chemistry and Biochemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA. In an effort to elucidate the importance of highly conserved residues in the protein sequence of cytochrome c, several site-67 analogs have been prepared using two different approaches. One procedure involves two cycles of Edman degradation on a non-heme peptide segment (66-104) derived from CNBr cleavage of the protected native protein. This is followed by coupling to synthetic dipeptides to introduce substitutions for Tyr-67. The second procedure involves preparation of a thirty-nine residue non-heme peptide by solid phase peptide synthesis. In both procedures, the synthetic non-heme peptide is coupled to the native heme-containing segment to yield the intact protein analog. Results of spectral, electrochemical, and kinetics characterization of the analogs will be discussed.
A b&acts
Go42
MODELS FOR PHOTOINDUCED ELECTRON TRANSFER: SYNTHESIS AND OPTICAL PROPERTIES OF QUINONE SUBSTITUTED, PHENYL LINKED PORPHYRIN DIMERS AND TRIMERS. Yigcent J,. CapMartin R. Johnson and Jonathan L. Sessler, Department of' Chemistry, University of Texas, Austin, Texas 78712 USA.
The synthesis of several quinone substituted, phenyl linked porphyrin dimers and trimers will be described. The well-defined interporphyrin configurations make these compounds suitable models for the study of multistep photoinduced electron transfer. This poster will present synthetic details associated with the preparation of these materials and results of optical analyses carried out with these new model systems.
6043
LONG-RANGE ELECTRON TRANSFER IN [CO(DIAMSAR)]-MODIFIED CYTOCHROME C DERIVATIVES. D. W. Conrad and R. A. Scott, Departments of Chemistry and Biochemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA. We have developed a carbodiimide-based procedure that results in covalent attachment of [Co(diAMsar)13+ complexes to surface glutamate or aspartate residues of horse cytochrome c. Seven singly modified derivatives have been prepared and characterized in terms of the distance between the attached cobalt cage complex and the heme. These distances range from -10 - 20 A. The rates of intramolecular electron transfer from Co(II) to heme Fe(II1) have been measured by flash photolysis using Ru(bpy)a*+ as photosensitizer. The distance dependence of this intramolecular electron transfer rate will be discussed and these results will be compared to other studies of long-range biological electron transfer.
G.044
SEMISYNTHETIC ANALOGS OF CYTOCHROME C: CHANGES AT RESIDUE 67. M. M. Frauenhoff and R. A. Scott, Departments of Chemistry and Biochemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA. In an effort to elucidate the importance of highly conserved residues in the protein sequence of cytochrome c, several site-67 analogs have been prepared using two different approaches. One procedure involves two cycles of Edman degradation on a non-heme peptide segment (66-104) derived from CNBr cleavage of the protected native protein. This is followed by coupling to synthetic dipeptides to introduce substitutions for Tyr-67. The second procedure involves preparation of a thirty-nine residue non-heme peptide by solid phase peptide synthesis. In both procedures, the synthetic non-heme peptide is coupled to the native heme-containing segment to yield the intact protein analog. Results of spectral, electrochemical, and kinetics characterization of the analogs will be discussed.