Result and discussion:
Substrate specificity
The substrate specificity for the PPO is represented in table. The Km values for catechol, L-DOPA, L-tyrosine, and p-Cresol are 4.12 × 10-3, 16.4 × 10-3, 6.12 × 10-3, and 5.01 × 10-3, respectively. Catechol was the best suited substrate, having the lowest Km value and highest Vmax value when compared to other 3 substrates (Table 1).
Table 1: Substrate specificity of PPO enzyme
Substrates Specific activity
(units mg-1 protein) Km
(µM) Vmax
(abs min-1)
Catechol 2300 4.12 X 10-3 3020
L-DOPA 430 16.40 X 10-3 990
L-Tyrosine 1930 6.12 X 10-3 2930
P-Cresol 2110 5.01 X 10-3 2983
Effect of Inhibitors
The effects of various compounds on the PPO activity were provided in Tables 2. Enzyme activity was markedly …show more content…
While the binding affinity increased in urea catechol complex, cysteine catechol complex and citric acid catechol complex when compared with their individual binding energies of -3.99 kJ mol-1, -0.87 kJ mol-1 and -1.27 kJ mol-1 respectively indicating lesser inhibition effect. The results are shown in table 5 and the interactions are shown in figure 5.
Table 5: Multiple substrate simultaneous docking
Compound Binding energy
(kJ mol-1) Intermol energy
(kJ mol-1) Total internal energy Torsional energy
(kJ mol-1) Energy of the unbound system RMS
Catechol+Ascorbic acid -2.37 -4.16 -0.25 +1.79 -0.25
Substrate specificity
The substrate specificity for the PPO is represented in table. The Km values for catechol, L-DOPA, L-tyrosine, and p-Cresol are 4.12 × 10-3, 16.4 × 10-3, 6.12 × 10-3, and 5.01 × 10-3, respectively. Catechol was the best suited substrate, having the lowest Km value and highest Vmax value when compared to other 3 substrates (Table 1).
Table 1: Substrate specificity of PPO enzyme
Substrates Specific activity
(units mg-1 protein) Km
(µM) Vmax
(abs min-1)
Catechol 2300 4.12 X 10-3 3020
L-DOPA 430 16.40 X 10-3 990
L-Tyrosine 1930 6.12 X 10-3 2930
P-Cresol 2110 5.01 X 10-3 2983
Effect of Inhibitors
The effects of various compounds on the PPO activity were provided in Tables 2. Enzyme activity was markedly …show more content…
While the binding affinity increased in urea catechol complex, cysteine catechol complex and citric acid catechol complex when compared with their individual binding energies of -3.99 kJ mol-1, -0.87 kJ mol-1 and -1.27 kJ mol-1 respectively indicating lesser inhibition effect. The results are shown in table 5 and the interactions are shown in figure 5.
Table 5: Multiple substrate simultaneous docking
Compound Binding energy
(kJ mol-1) Intermol energy
(kJ mol-1) Total internal energy Torsional energy
(kJ mol-1) Energy of the unbound system RMS
Catechol+Ascorbic acid -2.37 -4.16 -0.25 +1.79 -0.25