Which of the following situations would produce a Hill plot with a Hill coefficient (\(n_H\)) less than 1?

• A. A protein exhibiting positive cooperativity in ligand binding
• B. A protein exhibiting negative cooperativity in ligand binding
• C. A protein with a single ligand binding site
• D. A protein with non-cooperative (independent) ligand binding sites

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of the Hill coefficient (\(n_H\)). The Hill coefficient is a measure of cooperativity in ligand binding. If \(n_H > 1\), the protein exhibits positive cooperativity, meaning binding of one ligand increases the affinity for subsequent ligands. If \(n_H = 1\), the binding is non-cooperative, meaning each ligand binds independently. If \(n_H < 1\), the protein exhibits negative cooperativity, meaning binding of one ligand decreases the affinity for subsequent ligands.
2. Step 2: Analyze the situation where a protein exhibits positive cooperativity in ligand binding. Positive cooperativity results in a Hill coefficient greater than 1 (\(n_H > 1\)), so this situation would not produce a Hill plot with \(n_H < 1\).
3. Step 3: Consider the situation where a protein exhibits negative cooperativity in ligand binding. Negative cooperativity results in a Hill coefficient less than 1 (\(n_H < 1\)), so this situation would produce a Hill plot with \(n_H < 1\).
4. Step 4: Evaluate the situation where a protein has a single ligand binding site. A protein with only one binding site cannot exhibit cooperativity (positive or negative), as there are no additional binding sites to influence. This results in a Hill coefficient of exactly 1 (\(n_H = 1\)), indicating non-cooperative binding.
5. Step 5: Examine the situation where a protein has non-cooperative (independent) ligand binding sites. Non-cooperative binding means each ligand binds independently, resulting in a Hill coefficient of exactly 1 (\(n_H = 1\)). This situation would not produce a Hill plot with \(n_H < 1\).