Evaluation of the internal equilibrium constant for 3-oxo-delta 5-steroid isomerase using the D38E and D38N mutants: the energetic basis for catalysis.

@article{Hawkinson1994EvaluationOT,
  title={Evaluation of the internal equilibrium constant for 3-oxo-delta 5-steroid isomerase using the D38E and D38N mutants: the energetic basis for catalysis.},
  author={David C Hawkinson and Ralph M Pollack and Nicholas P. Ambulos},
  journal={Biochemistry},
  year={1994},
  volume={33 40},
  pages={12172-83}
}
The dissociation constant (KD) for the complex of the intermediate dienol (2) and the D38N mutant of 3-oxo-delta 5-steroid isomerase (D38N.2) has been determined for the isomerization of 5-androstene-3,17-dione (1). KD for D38N.2 is pH-dependent, with values of 6 nM at pH 6.9, 51 nM at pH 5.8, and 59 nM at pH 5.2. These values of KD are used to estimate the pH-independent dissociation constant (0.7 +/- 0.3 microM) for the complex of dienol and wild-type (WT) enzyme. The internal equilibrium… CONTINUE READING