TABLE 4

Substrate specificity of HADs from Sphingomonas sp. strain TDK1 and Sphingobium sp. strain TCM1

Substratea% of degraded substrate
TDK-HADbTCM-HADc
Tri(haloalkyl)
    Tris(1,3-dichloro-2-propyl) phosphate65100
    Tris(2-chloroethyl) phosphate031
    Tris(2,3-dibromopropyl) phosphate15100
Triaryl
    Tricresyl phosphate100100
    Triphenyl phosphate100100
Trialkyl
    Trimethyl phosphate316
    Triethyl phosphate12
    Tripropyl phosphate0.40
    Tributyl phosphate08
    Tris(2-butoxyethyl) phosphate00
    Tris(2-ethylhexyl) phosphate08
Other organophosphorus compounds
    Parathion methyl0d0d
    Parathion0d0d
    Paraoxon methyl0.002d14
    Paraoxon0.02d100
    Chlorpyrifos00
    Dichlorvos042
  • a The structures of organophosphates used in this experiment are shown in Fig. S2 in the supplemental material.

  • b The enzyme activity was assayed at 30°C for 30 min.

  • c The enzyme activity was assayed at 25°C for 30 min.

  • d The data were obtained by monitoring spectrophotometrically the liberation of p-nitrophenol from each compound at 405 nm.