FIG. 6.
Conversion of protocatechuate (λmax = 250 and 290 nm) to 2-hydroxy-4-carboxymuconic semialdehyde (λmax = 293 nm) by cell extracts of E. coli strain BL21 (DE3)(pLysS)(pRE1043) 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 protocatechuate. Spectra were recorded before the addition of 5 μl of extract (11 μg of protein) and after 0.17, 4, 8, 12, 16, 20, 24, 28, 32, 36, and 40 min.