Experimental and simulative dissociation of dimeric Cu,Zn superoxide dismutase doubly mutated at the intersubunit surface.

ABSTRACT: The equilibrium properties of dimeric Photobacterium leiognathi Cu,Zn superoxide dismutase mutant bearing two negative charges in the amino acid clusters at the association interface has been studied, experimentally and computationally, and compared to those of the native enzyme. Pressure-dependent dissociation is observed for the mutant, as observed by the fluorescence shift of the unique tryptophan residue located at the intersubunit surface. The spectral shift occurs slowly, reaching a plateau after 15-20 min, and is fully reversible. Measurement of the degree of dissociation allows us to calculate the standard volume variation upon association and the dissociation constant at atmospheric pressure. On the other hand the native protein is undissociable at any pressure. In the simulative

SUBMITTER: Maragliano L 

PROVIDER: S-EPMC1305382 | biostudies-literature | 2005 Apr

REPOSITORIES: biostudies-literature