Figure 6.

In Vitro Assays Conducted with Purified GGPS and PSY.

(A) Purified recombinant GGPS from S. alba (5 μg mL⁻¹) was combined separately with 3.3 μg mL⁻¹ purified wild type (Ala-191) and mutagenized Arabidopsis PSY (At-PSY_D191; see Figure 3C for positions) in a molar ratio of 2:1 GGPS/PSY. This showed the higher effectiveness of the system employing the PSY_D191 version as demonstrated by a tripling of the reaction velocity at identical protein concentrations. Data represent the mean ± se of phytoene productions from each of three independent GGPS and PSY purifications.

(B) SDS-PAGE of GGPS and At-PSY versions used in the enzymatic assays. GGPS was purified to homogeneity as published (Kloer et al., 2006) and the A₁₉₁D-mutagenized At-PSY version as given in Methods. Stain, Coomassie blue; M, molecular mass marker proteins.