ALDOSE REDUCTASE ENZYME'S CLINICAL AND THERMODYNAMIC CHARACTERISTICS IN THE SERUM OF IRAQI DIABETIC PATIENTS
A superfamily of aldo-keto reductases includes the monomeric NADPH-dependent cytosolic enzyme aldose reductase (AR). When hyperglycemia, increased glucose levels stimulate the AR, which activates the polyol pathway and results in glucose metabolism, the dangerous aldehydes created by reactive oxygen species (ROS) into innocuous alcohols. NADPH is a crucial cofactor in the formation of glutathione (GSH), a crucial antioxidant, and its consumption lowers GSH levels. The main causes problems of diabetes are osmotic stress brought on by the buildup of excess AR and oxidative stress brought on by a decline in the NADPH/NADP+ ratio and decreased NAD+. The aim of this work is to measure the AR enzyme's activity in healthy and diabetes patients. A spectrophotometric was used to measure the serum (AR) activity in 120 type II diabetes patients and 60 healthy individuals. Increase in serum (AR) is related to the body's internalized oxygen free radicals, which cause oxidative damage to human tissues. The thermodynamic constants of activation, ΔH, Ea, and ΔS, were calculated using the Arrhenius plot in order to reconcile our findings with the thermodynamic behavior of (AR) enzyme's. These values were found to be (10.55, 19.93, and 2.85) KJ/mol, respectively. Due to its capacity to change NADPH into NADH, the active polyol pathway in diabetes mellitus significantly contributes to the NADH/NAD+ redox imbalance. Lack of NADPH can cause oxidative stress via limiting glutathione metabolism, the excess NADH's ability to cause it generating ROS through the mitochondrial electron transport chain.
Keywords: Diabetes mellitus; Aldose reductase; Oxidative stress; Entropy; Enthalpy.