2,2-dipyridyl binding to metal substituted horse liver alcohol dehydrogenase |
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Authors: | C Syvertsen J S McKinley-McKee |
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Institution: | Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, Prague, Czechoslovakia |
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Abstract: | The binding of 2,2-dipyridyl to metal substituted horse liver alcohol dehydrogenase was measured by spectrophotometric titrations. Large changes in the visible absorption spectra were seen for the Co2+, Cu2+ and Ni2+ hybrids upon coordination of 2,2-dipyridyl, due to a change in coordination number. The formation constants for binding to the Co2+ and Cd2+ hybrids are of the order 10(6) M-1, which means that these hybrids have a 500-fold higher affinity for 2,2-dipyridyl than the native Zn2+ enzyme. 2,2-dipyridyl has a 100-fold higher affinity for enzyme bound Cd2+ than for aqueous Cd2+ ions, while for Cu2+ and Zn2+ the opposite is the case. None of the substituted metal ions were removed from the active site during titration with the chelator 2,2-dipyridyl. |
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Keywords: | Address reprint requests to Dr John S McKinley McKee Biokjemisk Institutt Universitetet 1 Oslo Pb 1041 Blindern Oslo 3 Norway |
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