Phosphorus nuclear-magnetic-resonance studies of a transition-state analogue complex of creatine kinase

Abstract
31P NMR spectra of MgADP bound to rabbit skeletal muscle creatine kinase in the presence of creatine and NO3- ions show that there are 2 non-identical forms of the bound nucleotide. The sites have different affinities for the nucleotide. MgADP at the high affinity site is in slow exchange (k [rate] < 125 s-1 at 27.degree. C) with free MgADP.