Table 2.

Substrate preferences of the three RHA1 hydrolases expressed in E. coli

SubstrateConcn (μM)a% Activity (U/mg of protein)b
EtbD1EtbD2BphD
HOHD15.6100 (65)100 (9.8)2.9
HPDA37.83.311100 (210)
HMSA13.81218<1
  • a Substrate concentrations were determined by using extinction coefficients as described in Materials and Methods.

  • b The relative activities are expressed as percentages of the specific activity either on HOHD (EtbD1 and EtbD2) or on HPDA (BphD). The values in parentheses are the absolute specific activities on the most preferred substrates. The enzyme activities were measured by using cell extracts from E. coli strains carrying plasmids pUAD1 (BphD), pUAD2 (EtbD1), and pUAD3 (EtbD2), as described in Materials and Methods.