**2. Oxidative stress**

#### **2.1 Oxidative damage to proteins**

Protein oxidation can lead to amino acid modification, fragmentation of the peptide chain, aggregation of cross-linked reaction products, and increased electrical charges. Oxidized proteins are more susceptible to proteolysis, and a raise in oxidized proteins may be responsible for the loss of selected physiological and biochemical roles. Free radical damage to proteins may play a role in the causation of cataracts and aging (**Figure 2**) [1, 6].
