title: 2,2-dipyridyl binding to metal substituted horse liver alcohol dehydrogenase.
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.
mesh_terms: D015082:2,2'-Dipyridyl / Q000378:metabolism*; D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D001665:Binding Sites; D002413:Cations, Divalent; D003035:Cobalt; D003300:Copper; D008099:Liver / Q000201:enzymology*; D008670:Metals; D009532:Nickel; D011725:Pyridines / Q000378:metabolism*; D013053:Spectrophotometry; D013329:Structure-Activity Relationship; D015032:Zinc
chemical_list: D002413:Cations, Divalent; D008670:Metals; D011725:Pyridines; D003035:Cobalt; D015082:2,2'-Dipyridyl; D003300:Copper; D009532:Nickel; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; D015032:Zinc