Table 2.

NAD+- and NADP+-dependent enzymatic oxidations of various α-hydroxy acids by the MJ1425-encoded enzyme, the MJ0490-encoded enzyme, and the MF-malate dehydrogenase

SubstrateCosubstrateaMJ1425 (MdhI)MJ0490 (MdhII)MF (MdhIII)
Km (mM)Vmax (U/mg)Vmax/Km (min−1 mg−1)Km (mM)Vmax (U/mg)Vmax/Km (min−1 mg−1)Km (mM)Vmax (U/mg)Vmax/Km (min−1 mg−1)
(S)-MalateNAD+ 0.02 ± 0.00411 ± 0.564800.15 ± 0.010.6 ± 0.0140.05 ± 0.121.9 ± 0.06437
(R)-MalateNAD+ 0.31 ± 0.093 ± 0.29 NDb NDNDND
(S)-MalateNADP+ 0.03 ± 0.0042 ± 0.04570.025 ± 0.005 3110NDND
(S)-SulfolactateNAD+ 0.04 ± 0.00622 ± 1.7551 NAc 0.07 ± 0.0151.6 ± 0.0822
(S)-SulfolactateNADP+ 0.39 ± 0.0062 ± 0.2664.6 ± 0.063 ± 0.221NDND
(S)-α-HydroxyglutarateNAD+ 0.52 ± 0.078 ± 0.415NANDND
  • a The cosubstrate concentrations were 1 mM NAD or 1 mM NADP.

  • b ND, not determined.

  • c NA, no activity detectable (<0.1 U/mg) at substrate concentrations of up to 10 mM.