Which statement regarding enzyme function is true?
1) Excessive salt ions can cause an enzyme to denature.
2) Enzymes cannot function at a pH lower than 6.
3) Higher temperatures allow greater contact between enzymes and substrates; therefore, the higher the temperature, the better the enzyme will function.
4) Most coenzymes are inorganic substances such as ions of iron or potassium.
The correct answer and explanation is:
The correct answer is 1) Excessive salt ions can cause an enzyme to denature.
Explanation:
Enzymes are proteins that act as biological catalysts, speeding up chemical reactions. They are highly sensitive to changes in their environment, including temperature, pH, and the concentration of ions. Let’s break down the statements:
- Excessive salt ions can cause an enzyme to denature: This is true. Enzymes have a specific three-dimensional structure that is crucial for their function. High concentrations of salt ions can disrupt the ionic bonds and interactions that maintain this structure, leading to denaturation. When denatured, an enzyme loses its shape and, consequently, its ability to bind to its substrate, rendering it inactive.
- Enzymes cannot function at a pH lower than 6: This statement is false. While enzymes have an optimal pH range, this range varies depending on the enzyme. Some enzymes, like those in the stomach (such as pepsin), work best at very acidic pH levels (around 1.5 to 2). Others, like those in the small intestine, work at a more neutral pH. Therefore, there is no universal pH cutoff of 6 for enzyme activity.
- Higher temperatures allow greater contact between enzymes and substrates; therefore, the higher the temperature, the better the enzyme will function: This statement is only partially true. While increasing temperature generally increases the rate of enzyme reactions due to greater molecular movement, extreme temperatures can denature the enzyme, losing its functional shape. Every enzyme has an optimal temperature at which it works most efficiently, and temperatures above or below this optimal range can reduce enzyme activity or destroy it altogether.
- Most coenzymes are inorganic substances such as ions of iron or potassium: This is false. Coenzymes are typically organic molecules, often derived from vitamins, that assist enzymes in catalyzing reactions. While some enzymes require metal ions (like iron or magnesium) as cofactors, these metal ions are not classified as coenzymes.
Thus, the first statement is the most accurate, as high salt concentrations can indeed lead to enzyme denaturation by disrupting its structure.