Isotope effects can yield detailed information about contacts made between a bound compound and its host receptor or enzyme. In this study, we have measured isotope effects upon the equilibrium constant for the association of glucose and human brain hexokinase [E.C.126.96.36.199] in the presence of β,γ-CH2-ATP and compared these with data for the same equilibrium in the absence of ATP-analogue. We have found isotope effects of 1.012, 0.929, 1.031, 1.052, 0.998, and 1.032 for the competitive binding of [1-3H]-, [2-3H]-, [3-3H]-, [4-3H]-, [5-3H]-, or [6,6-3H2]- and either [2-14C]- or [6-14C]glucose to brain hexokinase. We observed changes only at H1, H5, and H6, and we attribute these to a slight change in the position of Asn683 and Glu742 due to nucleotide binding and to partial satisfaction of activated OH6 by the terminal nucleotide phosphorus.
ASJC Scopus subject areas
- Colloid and Surface Chemistry