title: Molten globule monomers in human superoxide dismutase.
abstract: The time-resolved fluorescence decay and anisotropy of Cu/Zn human superoxide dismutase (HSOD) were studied as a function of temperature and denaturant concentration. In addition, circular dichroism (CD) measurements were performed on HSOD as a function of denaturant concentration in the amide and aromatic regions. The time-resolved fluorescence decay results reveal the existence of structural microheterogeneity in HSOD. Furthermore, CD measurements and a global analysis decomposition of the time-resolved fluorescence decay over denaturant concentration shows the presence of an intermediate in the unfolding of HSOD by guanidinium hydrochloride. Considering our previous measurements of partially denatured HSOD as a function of protein concentration (Mei et al., Biochemistry 31 (1992) 7224-7230), our results strongly suggest that the unfolding intermediate is a monomer that displays a molten globule state.
authors.affiliation: Mayo Clinic, Rochester, MN 55905.
authors.forename: N
authors.initials: N
authors.lastname: Silva
authors.forename: E
authors.initials: E
authors.lastname: Gratton
authors.forename: G
authors.initials: G
authors.lastname: Mei
authors.forename: N
authors.initials: N
authors.lastname: Rosato
authors.forename: R
authors.initials: R
authors.lastname: Rusch
authors.forename: A
authors.initials: A
authors.lastname: Finazzi-Agrò
mesh_terms: D002942:Circular Dichroism; D005454:Fluorescence Polarization; D019791:Guanidine; D006146:Guanidines / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D011487:Protein Conformation; D011489:Protein Denaturation; D013482:Superoxide Dismutase / Q000737:chemistry*; D013696:Temperature
chemical_list: D006146:Guanidines; D013482:Superoxide Dismutase; D019791:Guanidine