Pepsin was most active in acidic environment from 37 °C to 42 °C. The activity of pepsin was the highest in pH2.0, inactive above pH6.5, and completely denatured or irreversibly inactivated above pH8.0. Therefore, in the solution below pH8.0, pepsin can be reactivated after reacidification. The stability of pepsin at a high pH value is of great significance to the diseases caused by pharynx and larynx reflux. Learn more information at the Creative Enzymes website.