Enhanced Cytochrome C Oxidase Activity in WBC of COPD Patients


1 Clinical Biochemistry Department, Tarbiat Modares University, Tehran-Iran,

2 Clinical Biochemistry Department, Kurdistan University of Medical Sciences, Sanandaj-Iran,

3 Clinical Biochemistry Department, Tarbiat Modares University, Tehran-Iran

4 National Institute of Genetic Engineering and Biotechnology (NIGEB), TEHRAN-IRAN.


Background: Chronic obstructive pulmonary disease (COPD) is characterized by decreased expiratory flow rates, increased pulmonary resistance and hyperinflation. Cytochrome C Oxidase (COX) as a key oxidative enzyme modulates oxygen uptake and catalyzes the oxidation of reduced cytochrome C by molecular oxygen. In vitro studies indicate that the activity of COX can be directly regulated by the presence of molecular oxygen. Thus, a better understanding of the role of COX in patients with COPD can provide an important link between the availability of oxygen to tissues and the regulation of oxygen uptake and energy production in these patients. Materials and Methods: We studied 42 COPD patients (36 males, 6 females) with clinically stable conditions and 50 (42 males, 8 females) healthy sedentary volunteers of similar age. Whole blood was collected by venipuncture in sodium citrate tubes and WBCs were separated by Ficoll according to standard protocol and lysed with microtube pestle homogenizer. The homogenates were centrifuged and the supernatants were used as a cell extract for COX activity determination. Aliquots of this were assayed for total protein content and COX activity. Analysis of COX activity was performed using COX assay kit. Absolute specific COX activity was normalized for total protein. Relative activities were determined by dividing absolute specific COX activity on absolute specific citrate synthase activity. Results: Mitochondrial COX activity and specific activity (absolute and relative) significantly increased in WBCs of patients with COPD in comparison with control samples (p < 0.05). Conclusion: These results indicated that the activity of COX was increased in WBCs of patients with COPD but whether this is a primary or secondary change relevant to hypoxic condition in these patients is not clear and needs further investigation. (Tanaffos 2008; 7(3): 13-17)