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Table 1 Decarboxylation kinetics of branched-chain, aromatic, sulphur-containing and linear 2-oxo acids by cell extracts of S. cerevisiae strains expressing single 2-oxo acid decarboxylase genes

From: Comparative assessment of native and heterologous 2-oxo acid decarboxylases for application in isobutanol production by Saccharomyces cerevisiae

Substrate Strain K m (mM) V max (U mg protein−1) Hill coefficient (n) V max/K m (U mg protein−1 mM−1)
Pyruvate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 33.0 ± 3.61 0.03 ± 0.00 1.2 ± 0.4 0.00091
IME262 (kivD↑) BD BD NA NA
Phenylpyruvate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 0.20 ± 0.04 0.12 ± 0.01 1.0 ± 0.1 0.60
IME262 (kivD↑) BD BD NA NA
α-ketoisovalerate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 8.31 ± 1.34 2.34 ± 0.25 0.9 ± 0.1 0.28
IME262 (kivD↑) 7.73 ± 1.62a 0.03 ± 0.00a 2.7 0.0039
α-ketomethylvalerate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 3.49 ± 0.34 0.69 ± 0.07 0.8 ± 0.1 0.20
IME262 (kivD↑) 12.9 ± 2.87 0.05 ± 0.01 1.0 0.0039
α-ketoisocaproate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 0.57 ± 0.09 0.49 ± 0.00 1.0 0.86
IME262 (kivD↑) 2.42 ± 0.90 0.04 ± 0.01 1.2 0.017
4-methylthio-2-oxobutanoate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 1.43 ± 0.22 0.13 ± 0.00 1.1 0.091
IME262 (kivD↑) BD 0.01 ± 0.00b NA NA
2-oxobutanoate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 5.58 ± 0.58 0.10 ± 0.01 1.1 0.018
IME262 (kivD↑) BD BD NA NA
2-oxopentanoate IME259 (control) BD BD NA NA
IME260 (ARO10↑) BD BD NA NA
IME261 (kdcA↑) 1.44 ± 0.28 0.17 ± 0.00 1.1 0.12
IME262 (kivD↑) BD BD NA NA
  1. V max and K m values were estimated from non-linear fitting of data to the Michaelis–Menten equation or, where indicated, the Hill equation. The Hill coefficient (n) was calculated from the Hill equation, with n > 1 indicating positive cooperativity
  2. NA not applicable, BD below detection limit of 0.008 U mg protein−1
  3. aCalculated using the Hill equation
  4. bEnzyme activity at 25 mM substrate concentration