The greatest buffering capacity at physiological pH would be provided by a protein rich in which of the following amino acids?

Question

Quizplus · Accepted Answer

Histidine contains an imidazole ring as its R group. The nitrogen in this ring possesses a pKa around 6.0, thus it is able to accept or donate a proton at physiological pH. This fact makes the amino acid an ideal buffering component of a protein containing several histidine residues. Histidine has a side chain with a pKa around physiological pH (approximately 6.0), allowing it to effectively buffer changes in pH in biological systems.

The Greatest Buffering Capacity at Physiological PH Would Be Provided