Characterization of biosynthesized chitosan nanoparticles from Penaeus vannamei for the immobilization of P. vannamei protease: An eco-friendly nanobiocatalyst

Figures & data

Figure 1. a) Effect of pH on the activities of free (▲) and immobilized (■) enzyme. The activity at optimal pH was taken as 100%. b) Irreversible inactivation of free (▲) and immobilized (■) P. vannamei protease after incubation for different times at pH 3.0–12. The activity of untreated enzyme was taken as 100%.

Figure 2. a) Effect of temperature on the activities of free (▲) and immobilized (■) enzyme. The activity at optimal temperature was taken as 100%. b) Irreversible thermoinactivation of free (▲) and immobilized (■) P. vannamei protease at 30–90°C. The activity of the same enzyme solution, kept on ice, was considered as the control (100%).

Figure 3. a) Storage stability of free (lozenge) and immobilized (circles) P. vannamei protease at 4°C (solid) and at room temperature (hollow). b) Operational stability of immobilized P. vannamei protease on chitosan nanoparticles in subsequent 10 cycles.

Table 1 Kinetic parameters for free and immobilized forms of P. vannamei protease.

Enzyme form	Vmax (µM.min^−1)	kcat (s^−1)	Km (µM)	kcat/Km (µM^−1 s^−1)
Free	87 ± 0.37	132 ± 0.52	2.5 ± 0.15	52.8 ± 0.62
Immobilized	83 ± 0.41	128 ± 0.48	2.7 ± 0.17	47.4 ± 0.55

Figure 4. Turbidity levels in orange juice samples after treatment with free and immobilized enzyme over a period of 15 days of cold storage.