Correlation of Conformational Changes and Protein Degradation with Loss of Lysozyme Activity Due to Chlorine Dioxide Treatment.

Chlorine dioxide (ClO) is a potent oxidizing agent used for the treatment of drinking water and decontamination of facilities and equipment. The purpose of this research is to elucidate the manner in which ClO destroys proteins by studying the effects of ClO on lysozyme. The degree of enzyme activity lost can be correlated to the treatment time and levels of the ClO used. Lysozyme activity was drastically reduced to 45.3% of original enzyme activity when exposed to 4.3 mM ClO in the sample after 3 h. Almost all activities were lost in 3 h after exposure to higher ClO concentrations of up to 16.8 and 21.9 mM. Changes in protein conformation and amount as a result of ClO treatment were determined using the Raman spectroscopy and gel electrophoresis. Raman shifts and the alteration of spectral features observed in the ClO-treated lysozyme samples are associated with loss of the α-helix secondary structure, tertiary structure, and disulfide bond. Progressive degradation of the denatured lysozyme by increasing levels of chlorine dioxide was also observed in gel electrophoresis. Hence, ClO can effectively cause protein denaturation and degradation resulting in loss of enzyme activity.