Skip to main content

Table 2 Substrate specificity of the recombinant F6H Both rF6Hb and rF6Hy were purified on Ni-NTA resin then Superose 12, and fractions were assayed with the indicated substrates, using the direct enzyme assay.

From: Molecular characterization and functional expression of flavonol 6-hydroxylase

Substratea Relative enzyme activity (%)
  rF6Hb b rF6Hy c
3,7,4'-Trimethylquercetin 100 100
3,7-Dimethylquercetin 56 63
3,7,3',4'-Tetramethylquercetin 11 21
3-Methylquercetin 0 4
  1. aNo F6H activity was detected with kaempferol, quercetin, myricetin, naringenin, eriodyctyol, apigenin or luteolin when used as substrate, regardless of concentration. Rhamnetin (7-O-methylquercetin, 17% at 50 μM), tamarixetin (4'-O-methylquercetin, 13 % at 50 μM) and isorhamnetin (3'-O-methylquercetin, 4 % at 50 μM)
  2. bEstimated as 0.10 pkat/mg for 100% activity and 5 μM substrate.
  3. cEstimated as 0.19 pkat/mg for 100% activity and 5 μM substrate.