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Preparation and characterization of a ruthenium‐labeled Rhus stellacyanin
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)80566-6
Subject(s) - ruthenium , chemistry , ion , imidazole , stoichiometry , crystallography , stereochemistry , catalysis , organic chemistry
Reaction of Cu(II)‐stellacyanin with excess (NH 3 ) 5 Ru(H 2 O) 2+ yields a protein to which (NH 3 ) 5 Ru(III) is coordinated. The binding stoichiometry of Ru:Cu is (2.1 ± 0.1):1 as shown by ICP atomic emission measurements. In the 1 H‐NMR spectrum of the Ru(III)‐labeled protein, the signals from the C‐2H and C‐4H protons of His‐32 and His‐100 are absent. The ESR spectra of the native oxidized Cu(II)‐stellacyanin and of the Ru(III)‐labeled protein are identical in spite of the (NH 3 ) 5 Ru(His) 3+ ions being a low‐spin d 5 system. These data are interpreted as being the result of binding of two RU(III) ions to the modified stellacyanin at two proximal imidazole side‐chains which are within a separation distance that allows for their electronic coupling.