| Value |
2.5
mM
Range: ±0.5 mM
|
| Organism |
Rat Rattus norvegicus |
| Reference |
Alander et al., Microsomal glutathione transferase 1 exhibits one-third-of-the-sites-reactivity towards glutathione. Arch Biochem Biophys. 2009 Jul 1 487(1):42-8. p. 46 left column, top sentencePubMed ID19416719
|
| Method |
The pre-steady state kinetic properties of MGST1 [refs 20,21 in article] allows
the performance of single turn-over experiments where the enzyme,
equilibrated with various concentrations of GSH, is rapidly mixed with a stoichiometric (1/trimer) concentration of CDNB.
Upon mixing a rapid burst of product formation and release takes
place. Subsequent GSH rebinding to the empty site and slow thiolate
anion formation can then be observed (the rebinding phase is
shown in Fig. 5A). Fitting the GSH dependence of kobs for the thiolate
anion formation (Fig. 5B and Eqs. (2) and (3)) yielded the Kd for GSH (2.5±0.5mM). The presence of a low affinity site for GSH is
consistent with the mass spectrometry and structural data, and
was outside the sensitivity range for detection by conventional
equilibrium binding techniques. |
| Comments |
To summarise, GSH initially binds to each of the three low affinity
sites in MGST1 (Kd=50 mM). Once one molecule of bound GSH
is deprotonated (Kd=20µM), the remaining active sites bind their
GSH more strongly (Kd=2.5mM for the third GSH), but cannot
promote deprotonation. This results in one-third-of-sites reactivity. See BNID 105544, 105545, 105547 |
| Entered by |
Uri M |
| ID |
105546 |