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B I O C H E M IS T R Y
BALAKRlSHhAW 4YD VILLAFRANCA
Preparation and Characterization of Cobalt( 111)- and Chromium(II1)-Glutamine Synthetase Derivativest M. S. Balakrishnan and Joseph J. Villafranca*
ABSTRACT:Stoichiometric incorporation of Co(II1) into the n, metal ion sites of Escherichia coli glutamine synthetase (unadenylylated) was carried out by hydrogen peroxide oxidation of enzyme-bound Co(I1). This enzyme derivative was found to bind 1 mol of Mn(I1) per subunit to the n2 metalnucleotide sites with a KD value of 0.67 0.1 1 m M . The Co(II1)-enzyme was catalytically inactive (
