Identification of a reversible structural transition in the metal-depleted glycerol dehydrogenase from Bacillus stearothermophilus

Evidence is presented to demonstrate that the Zn 2+-depleted, inactive form of the glycerol dehydrogenase from Bacillus stearothermophilus exists in one of two possible conformations in equilibrium, the position of which is temperature sensitive. The conformation of the metal-depleted enzyme favoured by higher temperatures (20–40°C) is able to bind Zn 2+ and regain catalytic activity, whereas that favoured at lower temperatures (0–10°C) is unable to bind metal ions and is thus inactive. This equilibrium is also pH dependent with a p K of 6.6. At pH 6.0, the equilibrium lies in favour of the form of the enzyme able to bind metal ions and exhibit activity.