Table 2.

Effect of substrate length on PelW and Ogl activities

SubstrateEnzyme activitya± SD
PelWOgl
Vob (U · mg−1)Vmaxc(U · mg−1)Km c Vod(U · mg−1)Vmaxc(U · mg−1)Km c (μM)
G2057 ± 380 ± 5150 ± 30
G325 ± 230 ± 47 ± 2 μM10 ± 220 ± 7120 ± 50
G417 ± 223 ± 38 ± 2 μM4 ± 1.5 NDe ND
PGA14 ± 0.46 ± 20.01 ± 0.004 g liter−1 0
  • a No enzymatic activity was detected on any of these substrates when E. coli extracts from vector-only-carrying strains were used.

  • b The initial enzymatic rate of PelW was measured in 0.1 M Tris-HCl (pH 8.5) containing 0.1 mM MnCl2and either 0.5 g of PGA · liter−1 or 50 μM oligogalacturonate (Gn, where n = 2 to 4).

  • c For V max andKm determinations, PelW was incubated with PGA at concentrations of 0.005 to 0.025 g · liter−1 and with oligogalacturonates at concentrations ranging from 5 to 40 μM, while Ogl was incubated with oligogalacturonates at concentrations ranging from 50 to 400 μM.

  • d The initial enzymatic rate of Ogl was measured in 0.1 M Tris-HCl (pH 7) containing 0.1 mM MnCl2and either 0.5 g of PGA · liter−1 or 400 μM oligogalacturonate.

  • e ND, not determined because the activity of Ogl with these substrates was too low, which led to a high level of variability in the experimental data.