Unfolding and inactivation of monomeric superoxide dismutase from E. coli by SDS

The inactivation and the unfolding of the naturally monomeric Cu, Zn, super oxide dismutase from E. coli upon addition of sodium dodecylsulphate have b een studied. In contrast to the bovine enzyme, CD, EPR, NMR spectroscopy an d pulsed low resolution NMR measurements found an unfolding transition foll owed by inactivation of the enzyme. During this transition the active site becomes accessible to the bulk water. The unfolding is reversible and both, the tridimensional structure of the protein and the active site, can be re stored upon dialysis. In addition, unfolding occurs without loss of metals in the solution. (C) 2001 Elsevier Science BN. All rights reserved.