Wheatgerm Hexokinase (LII): Fluorimetric Measurement of the Binding of Substrates and Products

The change in intrinsic fluorescence observed when wheatgerm hexokinase combines with its substrates or products has been investigated. The dissociation constants for the enzyme · ligand complexes have been evaluated and found to be equal to their respective Michaelis constants, and confirm that fructose is the preferred hexose substrate. Both hexoses and nucleotides can bind independently to the enzyme and the data are consistent with previous proposals that conformation changes in the enzyme may accompany the random binding of substrates.