Figure 1.

Comparison of the substrate profiles of purified recombinant wild-type and Y131F paAzoR1. The percentage specific activity towards the best substrate for each enzyme was taken as 100%. Results are expressed as mean ± standard deviation from triplicate determinations. The enzymic reaction mixture (200 µl) contained 10 µg purified enzyme and 50 µM azo compound in 20 mM Tris–HCl pH 8.0, 0.3 M NaCl. The reaction was initiated by adding 0.5 mM NADPH for paAzoR1 and the loss of colour was assessed as described in §2.