Fibrinolytic enzyme from Arthrospira platensis: Kinetic and thermodynamic investigation

Abstract

Fibrinolytic enzymes from microorganisms have been investigated by their potential application as thrombolytic agents. Previous studies show that the fibrinolytic enzyme from Arthrospira platensis (FEAP) is stable at human physiological temperature (<50 °C) and pH (6.0–10.0). Understanding of the kinetic/thermodynamic characteristics is important to make the advances for industrial applications feasible. Therefore, a kinetic/thermodynamic analysis of FEAP was performed on the fibrin hydrolysis and enzyme thermoinactivation. Results showed two Michaelis-Menten-type profiles with two plateaus, revealing high affinity for the substrate with low Michaelis constant values (0.02 and 6.37 µg∙mL−1). The activation energy of the hydrolysis catalyzed by FEAP and the standard enthalpy variations of reversible enzyme unfolding were 49.65 and 107.01 kJ∙mol−1, respectively. When the temperature increased from 40 to 70 °C, the deactivation rate constant increased from 0.0050 to 0.0134 min−1, while the half-life decreased from 138.62 to 51.72 min. These results allowed to estimate the activation energy (E*d = 27.50 kJ∙mol−1), enthalpy (24.64 ≤ ΔH*d ≤ 24.89 kJ∙mol−1), entropy (−209.86 ≤ ΔS*d ≤ −210.10 J∙mol−1∙K−1), and Gibbs free energy (90.61 ≤ ΔG*d ≤ 96.74 kJ∙mol−1) of thermal denaturation. The data suggest that FEAP is a promising and thermostable biocatalyst that could be exploited for industrial applications.