Table 1.

Kinetic parameters for several substrates of THFA-DH fromR. eutropha strain Boa

SubstrateParameter
Km(mM)kcat/Km × 104 (M−1s−1)Ki (mM)
Primary alcohols
 Ethanolb3.13
n-Propanol0.036248ND
n-Butanol0.01559414.7
n-Pentanol0.0127883.2
n-Hexanol0.0144951.4
n-Heptanol0.0164131.9
Aldehydes
 Formaldehydeb1.932.3
 Acetaldehydeb0.075120
 Propionaldehyde0.0571598.2
 Butyraldehyde0.0332440.95
 Pentanal0.0611210.33
Secondary alcohols
 2-Propanol1.90.6ND
 2-Butanolb1.123.1
 2-Pentanol0.12998.6
 2-Hexanol0.081671.6
 2-Heptanol0.0582041.0
 2-Octanol0.0761291.3
O-heterocyclic compounds
 THF-2-alcohol0.0391382.2
 THF-3-alcohol0.05698ND
 Furfurylalcohol0.0251851.9
 Furfuraldehyde0.1471611.0
 Tetrahydropyran-2-alcohol0.0113861.5
Diols
 1,2-Butandiolb1.035
 1,3-Butandiolb0.4915
 1,4-Butandiolb0.2530
PEG 6000b0.557
  • a Activities were determined with homogeneous THFA-DH (18.8 nM) in 75 mM MOPS-NaOH, pH 8.2, and 5 mM CaCl2 under standard assay conditions with appropriate substrate concentrations. The apparent kinetic constants were determined by nonlinear curve fittings based on Michaelis-Menten kinetics. ND, not determined; —, no substrate inhibition detected under the conditions used.

  • b The curves were fitted based on the model of Michaelis and Menten. All other curves were fitted based on the model of substrate inhibition as described in Materials and Methods.