In a folded protein, a glutamate side chain has a of 7.2, substantially higher than its value in aqueous solution. Which feature of the side chain's microenvironment most likely causes this shift?
Select one answer.
Show answer and explanationHide answer and explanation
Answer: C (Burial of the glutamate side chain in a nonpolar pocket lacking a compensating charge)
Protonated glutamate is neutral, whereas deprotonated glutamate carries a negative charge. Burial in a nonpolar pocket lacking a compensating charge destabilizes the deprotonated form relative to the protonated form. Consequently, a higher pH is required for deprotonation, increasing the side chain's . An ion pair with arginine or a hydrogen bond that stabilizes the deprotonated carboxylate would instead lower the .