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Long‐range intramolecular electron transfer in Rhus vernicifera stellacyanin: A pulse radiolysis study
Author(s) -
Farver Ole,
Pecht Israel
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80567-8
Subject(s) - radiolysis , intramolecular force , chemistry , electron transfer , ruthenium , ion , photochemistry , imidazole , radical , copper , stereochemistry , catalysis , organic chemistry
The (NH 3 ) 5 Ru‐modified stellacyanin Ru(III) 2 ‐St[Cu(II)], where two ruthenium ions are coordinated to imidazole residues of His‐32 and 100, has been synthesized. CO − 2 radicals, generated by pulse radiolysis, react with the modified protein yielding an intermediate Ru(II)‐St[Cu(II)]. The rate ofmolecular electron transfer within this complex Ru(II)‐St[Cu(II)] k Ru(III)‐St[Cu(I)] has been determined, k u = 0.05 s −1 at 18°C, pH 7.0. The Ru(His‐32/100) to Cu(II) separation distance is relatively large (∼ 18 Å), and the driving force is low (10 kJ·mol −1 ), hence the correspondingly slow rate. This result is compared with those obtained in earlier studies of intramolecular fixed‐distance electron transfer reactions in blue copper proteins.