In an experiment to study the effect of proteases on proteins, what is the most likely effect of a major change in ph

The most likely effect of a major change in pH is a change in the configuration of the active sites of the enzyme.

Explanation:

Enzymes are mainly the molecules of protein, which mediate different chemical reactions that is, by enhancing the reaction rate inside the living organism's body. Protease refers to a protein-digesting enzyme, which functions on particular pH, for example pepsin functions on pH 2 inside the stomach, that is, highly acidic.  

An enzyme's shape determines its activity as they exhibit active sites that possess specific configurations, which fit in the substrate and lead to chemical reactions. A prime modification in pH can change the configuration of the active locations of the enzyme, making it sedentary.