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Table 1 Steady-state kinetic parameters of wild-type and mutant So BADH enzymes in the oxidation of BAL

From: Exploring the evolutionary route of the acquisition of betaine aldehyde dehydrogenase activity by plant ALDH10 enzymes: implications for the synthesis of the osmoprotectant glycine betaine

  Kinetic parameters
Enzyme Variable substrate k cat (s-1) Km(μM) k cat /Km(mM-1s-1)
  BAL    
Wild type   3.36 ± 0.13 98 ± 15 35 ± 4
A441C   2.99 ± 0.19 90 ± 6 33 ± 2
A441S   3.29 ± 0.12 119 ± 8 28 ± 3
A441T   2.64 ± 0.16 180 ± 6 15 ± 1
A441V   0.54 ± 0.05 512 ± 79 1.1 ± 0.3
A441F   0.29 ± 0.02 605 ± 26 0.48 ± 0.05
A441I   0.74 ± 0.05 1791 ± 115 0.41 ± 0.05
  NAD +    
Wild type   4.25 ± 0.16 22 ± 2 195 ± 8
A441C   2.20 ± 0.09 14 ± 1 179 ± 17
A441S   3.27 ± 0.18 29 ± 3 114 ± 20
A441T   2.39 ± 0.00 24 ± 4 100 ± 15
A441V   0.51 ± 0.00 6.4 ± 0.5 80 ± 5
A441F   0.39 ± 0.02 18 ± 1 22 ± 0
A441I   0.68 ± 0.03 2.8 ± 0.0 243 ± 11
  1. Initial velocities were obtained at 30°C in 50 mM HEPES-KOH buffer, pH 8.0, containing 0.1 mM EDTA. In the experiments with variable BAL, the fixed concentration of NAD+ was 0.2 mM, and in the experiments with variable NAD+ the fixed BAL concentrations were at least 10-times their appKm values estimated for each enzyme at fixed 0.2 mM NAD+. The apparent kinetic parameters were estimated by non-linear regression fit of the experimental data to the Michaelis-Menten equation. The values given in the Table are the mean ± standard deviation of the kinetic parameters estimated in two duplicate saturation experiments performed with enzymes from two different purification batches. Values for k cat are expressed per subunit.