Which of the following amino acid responsible for buffering action of hemoglobin is a major intracellular buffer of blood?
**Core Concept**
Hemoglobin, a crucial protein in red blood cells, plays a significant role in transporting oxygen to tissues. In addition to its oxygen-carrying capacity, hemoglobin also exhibits buffering action, helping to maintain acid-base balance in the body. This buffering action is attributed to the presence of specific amino acids within the hemoglobin molecule.
**Why the Correct Answer is Right**
The amino acid responsible for the buffering action of hemoglobin is Histidine. Histidine contains an imidazole side chain, which acts as a pH buffer by accepting or donating protons (H+ ions) depending on the pH of the surrounding environment. This ability to regulate pH helps maintain the acid-base balance in the blood. Histidine's buffering capacity is particularly important in the context of carbon dioxide transport, where it helps convert carbon dioxide into bicarbonate ions.
**Why Each Wrong Option is Incorrect**
**Option A:** Arginine - While an important amino acid in various bodily functions, Arginine is not directly responsible for the buffering action of hemoglobin.
**Option B:** Lysine - Lysine is a basic amino acid, but it is not primarily involved in the buffering action of hemoglobin.
**Option C:** Glycine - Glycine is a non-essential amino acid, but it does not contribute significantly to the buffering action of hemoglobin.
**Clinical Pearl / High-Yield Fact**
The buffering action of hemoglobin is a critical component of the body's acid-base regulation, and Histidine's role in this process is essential for maintaining proper pH levels in the blood.
**Correct Answer: C. Histidine**