Chloroplastic glutamine synthetase from Brassica napus.

Glutamine synthetase from roots of Brassica napus. Nucleotide sequence of a cytosolic isoform.

Purification and Characterization of Glutamine Synthetase Isoenzymes from Leaves and Roots of Brassica napus (L.)

Summary The glutamine synthetase enzymes from leaves (GS2) and roots (GSR) of Brassica napus L. have been purified to homogeneity by the application of a three-stage isolation procedure comprising anion-exchange chromatography, adsorption by hydroxylapatite and gel filtration on Sephacryl 5-300 HR. The isoforms of the enzyme show a differential distribution in leaf and root tissues. Elution profiles of hydroxylapatite chromatography showed a distinct behaviour for GS proteins found in leaves and roots. Denaturing SDS-PAGE and Western blot experiments revealed molecular masses of approximately 43.5 and 40.5 kD for GS2 and GSR subunits, respectively. Moreover, kinetic properties determined us…