Final answer:
Changing pH can cause proteins to denature, affecting their secondary and tertiary structures. Low pH changes hydrogen ion concentration, disrupting bonds in a protein and possibly leading to function loss or denaturation. Some of these changes are reversible; others are not, depending on the severity and nature of the change.
Step-by-step explanation:
When the pH of the environment surrounding a protein changes, the protein molecules can undergo a process known as denaturation. Denaturation refers to the disruption of a protein's secondary and tertiary structures without breaking the primary amino acid sequence. The secondary structure, including alpha-helices and beta-pleated sheets, is typically maintained by hydrogen bonds. A change in pH can disrupt these bonds. The tertiary structure, which gives the protein its three-dimensional shape, can be affected by a low pH as it changes the ionic and hydrophobic interactions.
Specifically, low pH levels can lead to an excess of hydrogen ions, which can disrupt the ionic bonds and hydrogen bonds that maintain the protein's structure. This leads to unfolding and potential loss of function, which in the case of enzymes can mean a decrease or loss of catalytic activity. While some proteins can refold back to their active form once normal pH is restored, others may denature irreversibly, an example being the digestion of proteins in the stomach where low pH is utilized to help break them down.