Table 1.

Properties of crotonyl-CoA carboxylase/reductase

ParameterRecombinant crotonyl-CoA carboxylase/reductase
Reductive carboxylation
    Specific activity (Vmax)40 units§ mg−1 (this study, tagged enzyme 100 units mg−1
    SubstratesCrotonyl-CoA (100% relative specific activity),acryloyl-CoA (40%)
Crotonyl-N-acetylcysteamine, methacryloyl-CoA, 6-hydroxycylohex-1-ene-1-carboxyl-CoA, cyclo-hexa-1,5-diene-1-carboxyl-CoA, acetoacetyl-CoA, propionyl-CoA, (R)-3-hydroxybutyryl-CoA, (S)-3-hydroxybutyryl-CoA (all <1%)
    Apparent Km values0.4 mM crotonyl-CoA (0.5 mM acryloyl-CoA); 0.7 mM NADPH; 14 mM HCO3 (equivalent to 0.2 mM ″dissolved CO2″ at pH 7.8)
    pH optimum7.5–8.0
    Molecular compositionNative molecular mass: 105 + 11 kDa, subunit molecular mass: 47 kDa
Reduction
    Specific activity3 units mg−1 (this study, tagged enzyme) 10 units mg−1 (according to ref. 8, nontagged enzyme)
    Apparent Km values0.2 mM crotonyl-CoA; NADPH not determined
  • §One unit corresponds to 1 mmol of product formed per min.