The Effect of Oxidative Stress Induced by Cigarette Smoking on the Activities of Hexokinas and Pyruvate Kinase Glycolytic Enzymes in Erythrocytes of Smokers

Hexokinase and pyruvate kinase are two regulatory enzymes of glycolytic pathway in erythrocytes. Increasing evidence suggests that cigarette smoking which produces free radicals and oxidative stress can cause damage to body macromolecules such as proteins and enzymes. The aim of the present study was to investigate the susceptibility of key enzymes of erythrocytes glycolytic pathway(hexokinase and pyruvate kinase) in smokers. Patients & Sixty-five smokers and 65 age and sex-matched healthy non-smokers were enrolled in the study. The total activities of hexokinase and pyruvate kinase and total plasma antioxidants were measured and then compared in both smokers and non-smokers. Results showed that hexokinase activity and total plasma antioxidants were significantly lower in smokers than non-smokers, but the activity of pyruvate kinase did not differ significantly from values obtained in non-smokers. The activities of hexokinase and pyruvate kinase were positively correlated with the total plasma antioxidants. The activity of hexokinase and total plasma antioxidant were negatively correlated with duration and also with cigarette number smoking per day, but there was not any significant correlation between activity of pyruvate kinase and duration and also cigarette number smoking per day. It seems that smokers undergo an important oxidative stress due to cigarette smoking. Also, free radicals produced in this process can damage the structure of hexokinase and then reduce hexokinase activity in erythrocytes of smokers. It seems that pyruvate kinase has more stability than hexokinase, and its activity does not differ significantly in smokers from non-smokers.