Fig. 2

Activities of the B. thuringiensis kinase (DrdK), isomerase (DrdI), and aldolase (DrdA). a Coupled assay of DHAP formation from 5-deoxyribose when DrdK (K), DrdI (I), DrdA (A), and ATP are present in the reaction. DHAP formation was tracked via glycerol 3-phosphate dehydrogenase-catalyzed oxidation of NADH. Standard deviation for each point was <5 µM NADH. b DrdK is specific for 5-deoxyribose (5-dR) and 5-methylthioribose (MTR). Reactions contained 0.5 mM sugar and 1 mM ATP. Activity against 5-deoxyribulose (5-dRu) was undetectable (†), as was activity against 2-deoxyribose, ribose, fucose, fructose, fructose 6-phosphate, and glucose. Data are corrected for the ATPase activity of DrdK and are the mean of three replicates; error bars are the s.d. c DrdA prefers Mn²⁺ or Co²⁺ as cofactor. The enzyme was prepared from E. coli grown in unsupplemented LB, isolated by Ni²⁺-affinity chromatography, desalted and dialyzed against EDTA to remove metals. Activity was then assayed without (NA) or with 0.1 mM metal chloride (or 2 mM for MgCl₂, to mimic intracellular levels). The activity of the undialyzed enzyme (ND) is also shown. Data are the mean of three replicates; error bars are the s.d. d The substrate preference of DrdA, measured by the loss of DHAP after 10 min from reactions containing 1 mM DHAP and 1 or 3 mM aldehyde (identified by prefix). Data are the mean of three (or for acetaldehyde six) replicates; error bars are the s.d. Significance was determined by t-test, *P < 0.05, **P < 0.01, ***P < 0.001