title: Head-to-tail and side-by-side oligomerization of human carbonic anhydrase II: a small angle X-ray scattering study.
abstract: Solvent-induced directional aggregation of human carbonic anhydrase II (hCA) was studied by small angle X-ray scattering and fluorescence and fourth-derivative ultraviolet absorption spectroscopy. We propose that hCA at 5 mg ml(-1) in pure water forms head-to-tail oligomers built up, on average, by four to five monomers. At higher protein concentrations, the oligomers associate pair-wise and side-by-side. Spectroscopic evidence suggests that the subunits forming the aggregates are tightly folded, but with a structure that differs, at least locally, from the native state. A more complex aggregation pattern was observed under solvent conditions that favor the removal of zinc from the enzyme-active site, conditions under which the subunits are significantly less compact than in water. hCA may provide a useful model to investigate the effects of additives and genetic manipulation on protein aggregation.
authors.affiliation: Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C.67, 1900, La Plata, Argentina. marcelo@fisica.unlp.edu.ar
authors.forename: M
authors.initials: M
authors.lastname: Ceolín
authors.forename: U S
authors.initials: US
authors.lastname: Colombo
authors.forename: M C
authors.initials: MC
authors.lastname: Frate
authors.forename: E
authors.initials: E
authors.lastname: Clérico
authors.forename: E
authors.initials: E
authors.lastname: Antón
authors.forename: M R
authors.initials: MR
authors.lastname: Ermácora
mesh_terms: D001665:Binding Sites; D002256:Carbonic Anhydrases / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017510:Protein Folding; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry; D014965:X-Rays; D015032:Zinc / Q000737:chemistry
chemical_list: D014867:Water; D002256:Carbonic Anhydrases; D015032:Zinc