Preferred sites and pathways for electron transfer in blue copper proteins
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Preferred sites and pathways for electron transfer in blue copper proteins. / Farver, O; Pecht, I.
In: Progress in clinical and biological research, Vol. 274, 1988, p. 269-83.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Preferred sites and pathways for electron transfer in blue copper proteins
AU - Farver, O
AU - Pecht, I
PY - 1988
Y1 - 1988
N2 - Long-range electron transfer reactions proceed within and between metalloproteins at relatively fast rates and with marked specificities. The blue single copper proteins are well known electron carriers with their redox center being of limited accessibility to solvent and solutes. The question of where and how electrons are transferred to and from the copper-ion have been investigated. One experimental approach developed in order to pursue these problems is that of reductively labeling several representative, yet structurally distinct blue single copper proteins; azurin, plastocyanin, and stellacyanin with chromium ions. In all three cases, a substitution inert Cr(III)-adduct is formed when the oxidized protein is reduced by Cr(II)ag ions. In azurin, Cr(III) binds to the Glu-91 carboxylate approximately 10 A from the copper center. In both plastocyanin and stellacyanin the Cr(III) label is most probably also coordinated to carboxylate groups, present in plastocyanin, and in stellacyanin 12 A and 6 A, respectively, from the copper center. The salient feature emerging from examination of the three copper proteins is that a pi-facilitated electron transfer (E.T.) pathway may be operative; in azurin, E.T. proceeds via an extended imidazole ring system, and in plastocyanin and stellacyanin via a weakly coupled pi-system. Therefore, a case emerges for suggesting that this is the common feature of the long-distance intramolecular E.T. in this class of metalloproteins. These pathways are most probably a regulatory alternative to the E.T. site recognized at the exposed, "Northern" imidazole coordinated to copper in all these proteins.
AB - Long-range electron transfer reactions proceed within and between metalloproteins at relatively fast rates and with marked specificities. The blue single copper proteins are well known electron carriers with their redox center being of limited accessibility to solvent and solutes. The question of where and how electrons are transferred to and from the copper-ion have been investigated. One experimental approach developed in order to pursue these problems is that of reductively labeling several representative, yet structurally distinct blue single copper proteins; azurin, plastocyanin, and stellacyanin with chromium ions. In all three cases, a substitution inert Cr(III)-adduct is formed when the oxidized protein is reduced by Cr(II)ag ions. In azurin, Cr(III) binds to the Glu-91 carboxylate approximately 10 A from the copper center. In both plastocyanin and stellacyanin the Cr(III) label is most probably also coordinated to carboxylate groups, present in plastocyanin, and in stellacyanin 12 A and 6 A, respectively, from the copper center. The salient feature emerging from examination of the three copper proteins is that a pi-facilitated electron transfer (E.T.) pathway may be operative; in azurin, E.T. proceeds via an extended imidazole ring system, and in plastocyanin and stellacyanin via a weakly coupled pi-system. Therefore, a case emerges for suggesting that this is the common feature of the long-distance intramolecular E.T. in this class of metalloproteins. These pathways are most probably a regulatory alternative to the E.T. site recognized at the exposed, "Northern" imidazole coordinated to copper in all these proteins.
KW - Azurin
KW - Bacterial Proteins
KW - Binding Sites
KW - Electron Transport
KW - Metalloproteins
KW - Models, Molecular
KW - Plastocyanin
KW - Protein Binding
KW - Protein Conformation
M3 - Journal article
C2 - 3406028
VL - 274
SP - 269
EP - 283
JO - Progress in Clinical and Biological Research
JF - Progress in Clinical and Biological Research
SN - 0361-7742
ER -
ID: 113626786