Purification and characterization of ribulose-1,5-bisphosphate carboxylase from triticale

Ribulose-1,5-bisphosphate carboxylase has been isolated from a synthetic cereal triticale and purified using a newly developed rapid procedure involving precipitation with ammonium sulphate (35-55% saturation), DEAE-cellulose (DE-52) chromatography and filtration through Sepharose CL-68. Molecular weights of the enzyme subunits are 15.5 and 52 kDa which corresponds to 540 kDa for the hexadecameric holoenzyme. Isoelectric focussing showed that the enzyme has a pI of 4.2. Various kinetic constants determined under aerobic conditions are: Km (CO2), 118 microM; Km (RuBP), 220 microM (at 20 mM NaHCO3) and Vmax, 690 nmole CO2 fixed/mg enzyme/min.