title: Hemocyanin from E. californicum encapsulated in silica gels: oxygen binding and conformational states.
abstract: Cooperativity depends on the existence of equilibria among functionally distinct conformational states that are affected by homo and heterotropic effectors. In order to isolate the quaternary conformations of hemocyanin from E. californicum, the 24-meric giant protein was encapsulated in wet, nanoporous silica gels, either in the absence or presence of oxygen. The deoxy- and oxy-hemocyanin gels exhibit a p50 for oxygen of 11 and 2.5 torr, respectively, values in close agreement with those for hemocyanin in solution. The observed Hill coefficients are lower than unity, indicating a conformational heterogeneity within each locked conformational state, a finding in agreement with the assumption that at least four conformational states are required to explain the oxygen binding properties of E. californicum hemocyanin in solution.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Parma, Parma, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Ronda
authors.forename: Serena
authors.initials: S
authors.lastname: Faggiano
authors.forename: Stefano
authors.initials: S
authors.lastname: Bettati
authors.forename: Nadja
authors.initials: N
authors.lastname: Hellmann
authors.forename: Heinz
authors.initials: H
authors.lastname: Decker
authors.forename: Tilo
authors.initials: T
authors.lastname: Weidenbach
authors.forename: Andrea
authors.initials: A
authors.lastname: Mozzarelli
mesh_terms: D000465:Algorithms; D000818:Animals; D005782:Gels / Q000737:chemistry; D006433:Hemocyanins / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013053:Spectrophotometry; D013112:Spiders / Q000737:chemistry*
chemical_list: D005782:Gels; D012996:Solutions; D012822:Silicon Dioxide; D006433:Hemocyanins; D010100:Oxygen