Lina N. Al-Kasimy Layla A. Al Jebur Firas Taher Maher


A kinetic and thermodynamic study was conducted for the enzyme partially purified from heart patients by gel filtration and dialysis. It was found that the optimal concentration of the enzyme was (0.8M), and the optimal concentration of polyphenols to inhibit the purified enzyme was (5M). The values of Km and Vmax for the purified enzyme are (Km=0.243M) and (Vmax=1.5197 M/min). The optimum temperature for enzyme action was (40°C), while the optimum pH was (7.4). The thermodynamic results of the purified enzyme showed that the activation energy is 74545J.K-1.mol-1 and the activation enthalpy for the transition state of the ES complex was 9818 J.mol-1, while the activation entropy for the transition state was 57.557 + KJ.K-1.mol-1, And the value of the free energy of the transition state is 14.568 - Kj.mol-1. The positive value of enthalpy indicates that the enzymatic reaction is energy-absorbing. In contrast, the positive value of entropy suggests that the enzyme complex ES is less regular than the enzyme and the substrate and more random, while the negative value indicates free energy offers that the course of the reaction towards the formation of the enzyme complex is automatic, that is, it does not need to be equipped with energy. The study aimed to study the kinetics of the enzyme lactate dehydrogenase purified from the serum of heart patients, such as temperature, pH, and concentration of the substrate, as well as calculating the Michaelis-stencil constant Km for the enzyme and the maximum speed Vmax and then extracting polyphenol compounds from pomegranate peels and studying their effect on the activity of lactate dehydrogenase enzyme purified from serum of heart patients. And a study of the thermodynamic parameters of the enzyme lactate dehydrogenase purified from the serum of heart patients.

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Lactate Dehydrogenase (LDH), Inhibition, Polyphenols, Thermodynamic properties.

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