title: Characterization of superoxide dismutase 1 (SOD-1) by electrospray ionization-ion mobility mass spectrometry.
abstract: In this paper, we report nano-electrospray ionization-ion mobility mass spectrometry (nano-ESI-IM-MS) characterization of bovine superoxide dismutase (SOD-1) and human SOD-1 purified from erythrocytes. SOD-1 aggregates are characteristic of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease in humans that could be triggered by dissociation of the native dimeric enzyme (Cu(2),Zn(2)-dimer SOD-1). In contrast to ESI-MS, nano-ESI-IM-MS allowed an extra dimension for ion separation, yielding three-way mass spectra (drift time, mass-to-charge ratio and intensity). Drift time provided valuable structural information related to ion size, which proved useful to differentiate between the dimeric and monomeric forms of SOD-1 under non denaturing conditions. In order to obtain detailed structural information, including the most relevant post-translational modifications, we evaluated several parameters of the IM method, such as sample composition (10 mM ammonium acetate, pH 7) and activation voltages (trap collision energy and cone voltage). Neutral pH and a careful selection of the most appropriate activation voltages were necessary to minimize dimer dissociation, although human enzyme resulted less prone to dissociation. Under optimum conditions, a comparison between monomer-to-dimer abundance ratios of two small sets of blood samples from healthy control and ALS patients demonstrated the presence of a higher relative abundance of Cu,Zn-monomer SOD-1 in patient samples.
authors.affiliation: Department of Analytical Chemistry, University of Barcelona, Diagonal 647, 08028, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Borges-Alvarez
authors.forename: Fernando
authors.initials: F
authors.lastname: Benavente
authors.forename: Marta
authors.initials: M
authors.lastname: Vilaseca
authors.forename: José
authors.initials: J
authors.lastname: Barbosa
authors.forename: Victoria
authors.initials: V
authors.lastname: Sanz-Nebot
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000097:blood / Q000201:enzymology; D000818:Animals; D016022:Case-Control Studies; D002417:Cattle; D004912:Erythrocytes / Q000737:chemistry / Q000201:enzymology; D005260:Female; D006801:Humans; D007477:Ions / Q000737:chemistry; D008297:Male; D011487:Protein Conformation; D055503:Protein Multimerization; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013482:Superoxide Dismutase / Q000097:blood* / Q000737:chemistry*; D000072105:Superoxide Dismutase-1
chemical_list: D007477:Ions; C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1