Organic Chemistry MCAT Practice Exam

Denaturation of proteins refers to the structural alteration of the protein that results in the loss of its biological function, typically caused by factors such as temperature, pH, and certain chemicals. High temperature is a well-known factor that can lead to denaturation; as the temperature increases, kinetic energy rises, which can disrupt the weak interactions (such as hydrogen bonds and van der Waals forces) that maintain the protein's tertiary and quaternary structure. This disruption ultimately leads to a loss of the protein’s functional conformation.

The other factors listed may also contribute to protein denaturation, but they do not do so exclusively or as effectively as high temperature might. High pH can lead to denaturation as well, but it is not the sole factor; it can disrupt ionic bonds and hydrogen bonding within the protein structure. Presence of proteases refers to enzymes that break down proteins, which can lead to complete degradation rather than simple denaturation. Low salt concentration does not typically cause denaturation and, in some cases, may help stabilize protein structure by preventing aggregation.

Therefore, high temperature stands out as a definitive and direct cause of protein denaturation, making it the most accurate choice in this context.