Enzyme inactivation by TiO2 photosensitization.

Area of Science:

• Biochemistry
• Photochemistry
• Materials Science

Background:

• Horseradish peroxidase (HRP) is a widely used enzyme in biochemical assays.
• Titanium dioxide (TiO2) is a common UV-blocking agent in sunscreens and cosmetics.
• UVA exposure can impact the stability and function of biological molecules.

Purpose of the Study:

• To investigate the effect of UVA exposure on horseradish peroxidase (HRP) in the presence of titanium dioxide (TiO2).
• To determine the role of reactive oxygen species (ROS) in the observed inactivation of HRP.

Main Methods:

• Enzymatic activity assays were performed on HRP solutions exposed to UVA light.
• Experiments were conducted with and without the addition of TiO2.
• The influence of air (oxygen) on the inactivation process was examined.

Main Results:

• Horseradish peroxidase (HRP) showed significant inactivation when exposed to UVA light in the presence of TiO2.
• The presence of air enhanced the inactivation rate, suggesting the involvement of reactive oxygen species (ROS).
• TiO2, a common sunscreen ingredient, exacerbates UVA-induced HRP damage.

Conclusions:

• UVA exposure in the presence of TiO2 leads to substantial inactivation of HRP.
• Reactive oxygen species (ROS) play a critical role in the photodegradation of HRP.
• Findings highlight potential risks for HRP-containing products exposed to sunlight and TiO2.