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Table 2 Specific activities and kinetic parameters of wild-type AbOPH and its variants

From: Marked enhancement of Acinetobacter sp. organophosphorus hydrolase activity by a single residue substitution Ile211Ala

Enzymes Specific activity (U/mg) K M (μM) k cat (min−1) k cat/K M (min−1 μM−1)
AbOPH ND ND ND
AbOPHI211A 1.060 ± 0.023 103 ± 14 93.2 ± 3.2 0.90
AbOPHL156M 0.0115 ± 0.0010 45.5 ± 5.6 0.862 ± 0.031 0.018
AbOPHH268L 0.0104 ± 0.0011 56.7 ± 7.0 0.804 ± 0.030 0.013
  1. Specific activities of purified enzymes were measured toward 0.5 mM MP
  2. The kinetic parameters were determined by measuring purified enzyme activities toward MP at concentration from 0.01 to 1 mM and fitting data to the Michaelis–Menten equation. All enzymatic assays were performed at least in triplicate and average values were adopted
  3. ND no enzymatic activity was detected except spontaneous hydrolysis, in spite of the high enzyme loading (2 mg/mL)