FIG. 5.
Conversion of 3,4-dihydroxyphthalate (λmax = 309 nm) to protocatechuate (λmax = 250 and 290 nm) by cell extracts of E. coli strain BL21 (DE3)(pLysS)(pRE1026) at 30°C. The sample and reference cuvettes contained 50 mM potassium-sodium-phosphate buffer (pH 6.8) in 1-ml volumes. The sample cuvette also contained 100 nmol of 3,4-dihydroxyphthalate. Spectra were recorded before the addition of 5 μl of extract (14 μg of protein) and after 0.17, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, and 26 min.