Similarity of Ribulose-1,5-bisphosphate Carboxylases of Isogenic Diploid and Tetraploid Ryegrass (Lolium perenne L.) Cultivars

Abstract

Partially purified ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) was isolated from diploid cultivars of ryegrass (L. perenne L.) using 2 separate methods. The apparent Km (CO2) values for the enzymes prepared by either method did not differ significantly between diploid and tetraploid when assayed by 2 separate techniques. The unpurified enzymes from freshly lysed (and fully functional) protoplasts of both diploid and tetraploid cultivars gave virtually identical apparent Km (CO2) values. There was no indication of large differences in affinity for CO2 of illuminated intact protoplasts from the 2 cultivars.