FIG. 2.

Denaturing gel electrophoresis of proteins expressed by the different plasmids. The proteins were stained with Coomassie brilliant blue. The structures of the epimerases were as follows: lane A, R₃A₂ (pHE51); lane B, A₂R₄ (pHE56); lane C, R₃A₂R₄ (pHE27); lane D, A₂ (pHE58); lane E, A₁ (pHE42); lane F, A₁R₁ (pHE29); lane G, A₁R₁R₂ (pHE35); lane H, A₁R₁R₂R₃ (pHE37); lane I, A₁R₁R₂R₃A₂ (pHE57); lane J, A₁R₁R₂R₃A₂R₄ (pHH1). Six micrograms of protein was loaded in each lane. The proteins were partially purified by ion-exchange chromatography, except for the epimerase in lane B, which was further purified by gel filtration (11). The numbers indicate molecular masses (in kilodaltons) of a molecular mass standard.