Carbon Nanotubes Inhibit the Pepsin Activity at High Ionic Strength

Abstract

Gastroesophageal reflux disease (GERD) is a common chronic gastrointestinal disorder in adults that occurs as the stomach contents reflux and come up into the esophagus due to a dysfunction in the lower oesophageal sphincter. One approach commonly used to treat GERD is inhibition of the activity of pepsin enzyme. Carbon nanotubes (CNTs) are nanoparticles of carbon atoms that possess numerous interesting physical and chemical properties. CTNs functionalization expands the range of their properties to make them soluble in biological fluids and to confer the property of carrying drug or biological macromolecules which increase the scope of their applications in biomedical science. This study aims to utilize CNTs as a pepsin inhibitor and as a new medication for the treatment of GERD. The pepsin activity before and after the addition of an exact amount of the CNTs to the reaction mixture was measured colorimetrically. The results showed that both Vmax and Km changed after the addition of CNTs to the pepsin solution indicating a mixed inhibition of pepsin activity. This finding pointed to the ability of CNTs to bind with the pepsin molecule and pepsin-protein complex, therefore inhibiting the enzyme activity. The findings also demonstrated a complete inhibition of pepsin activity by CNTs when increasing the ionic strength of the reaction mixture. It can be inferred that using CNTs at a high concentration of NaCl at 37°C is the optimal condition for pepsin inhibition.