Impact of pH on Protein Solubility and Amino Acid Charge

Very Hard Biochemistry Amino Acids And Proteins

A recent research study has isolated a novel protein from a rare species of plant. This protein is unique due to its **unusual amino acid composition**, which includes a high proportion of **hydrophobic** and **basic residues**. Intriguingly, preliminary tests suggest that this protein undergoes conformational changes under varying pH conditions, leading to alterations in its solubility. The study further emphasizes that it has a high **isoelectric point (pI)** compared to typical plant proteins.

Considering the structure and properties of amino acids, particularly in relation to pH and protein solubility, which of the following amino acid characteristics most directly explains the **altered solubility** of this protein at different pH levels?

The hydrophobic interactions among the amino acids become weaker at lower pH.

The recruitment of protons to basic residues at lower pH leads to increased positive charge.

The solubility is unaffected by the molecular weight of the amino acids.

Hydrogen bonding interactions among hydrophilic residues remain constant across all pH levels.

Hint

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