Studies on the subunit structure of ribulose-1,5-diphosphate carboxylase from the blue-green alga Microcystis aeruginosa.

Ribulose-1,5-diphosphate carboxylase (EC 4.1.1.39) has been purified from the unicellular blue-green alga Microcystis aeruginosa by ammonium sulphate precipitation, followed by linear sucrose density gradient centrifugation. The enzyme has a molecular weight of 518, 000 and contains two types of subunits (large, 50,000 and small, 14,000) as shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis. The enzyme from this photosynthetic prokaryote thus appears to resemble closely the ribulose, diphosphate carboxylase of eukaryotic microalgal chloroplasts in quaternary structure.