title: Isolation of the catalytically competent small subunit of ribulose bisphosphate carboxylase/oxygenase from spinach under an extremely alkaline condition.
abstract: A method for isolating the small subunit (B) of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) from spinach leaf using an alkaline buffer (pH 11.2) in combination with sucrose gradient centrifugation is described. Although the yield of isolated subunit B (ca. 20%) was comparable to that previously described (ca. 25%) using the acid precipitation method [Andrews, T.J. and Lorimer, G.H. (1985) J. Biol. Chem. 260: 4632-4636], the isolated subunit B in this report suffered less denaturation (ca. 30%) as estimated from kinetic analysis of its reassembly with large subunit (A) derived from Aphanothece halophytica. Studies on the kinetic properties of the reassembled enzyme molecules suggested that spinach subunit B does not influence the affinity of the enzyme for substrate CO2. The catalytic core (A8) of spinach RuBisCO could not be isolated in the native form.
authors.forename: A
authors.initials: A
authors.lastname: Incharoensakdi
authors.forename: T
authors.initials: T
authors.lastname: Takabe
authors.forename: T
authors.initials: T
authors.lastname: Takabe
authors.forename: T
authors.initials: T
authors.lastname: Akazawa
mesh_terms: D002499:Centrifugation, Density Gradient; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046911:Macromolecular Substances; D008433:Mathematics; D010105:Oxygenases / Q000302:isolation & purification*; D010944:Plants / Q000201:enzymology*; D014675:Vegetables
chemical_list: D046911:Macromolecular Substances; D010105:Oxygenases