Figure 3.
MauG catalyzes insertion of the second oxygen at the C6 position of βW57. Reaction mixtures contained 10 μM MADH β subunit monohydroxylated biosynthetic intermediate,9 1 μM MauG and 60 μM NADH. (A) The reaction was carried out in the presence of 16O2 (green) or 18O2 (blue). (B) The reaction was carried out in buffer containing either H216O (green) or H218O (blue). Sample preparation and mass spectrometry analysis were as previously described.9 The larger mass of the mature subunit relative to that in Figure 2 is because the biosynthetic intermediate used as substrate in this experiment included a 6xhistidine C-terminal tag.