Effect of Proteolysis in Erythrocyte Damage of Diabetic Complications

Diabetes is a complex metabolic disorder character- ized by defects in the body’s ability to control glucose and insulin homeostasis, and it is estimated that in the future, the annual incidence rate of diabetes will con- tinue to increase worldwide. Currently, it is believed that various complications of diabetes mellitus result from oxidative stress wherein increased free radical produc- tion is coupled with low levels of cellular antioxidants (1). Because the human erythrocyte plays a role as an O2 and CO2 transporter, it is constantly exposed to reac- tive oxygen species (ROS) and oxidative stress. Oxidative stress occurs in cells or tissues when ROS concentration exceeds antioxidant concentration (2). Oxidant damage to proteins makes them more vulnerable to proteolytic degradation by enzymes that recognize modifications like conformational changes and fragmentation. A com- bination of increased oxidant production and decreased antioxidant levels in the erythrocytes in a diabetes mel- litus patient contributes to the vulnerability of glycated hemoglobin to oxidant damage and subsequent pro- teolytic degradation. Oxidant-damaged hemoglobin is