Hemoglobin is the remarkable protein that makes oxygen transport possible. This complex quaternary protein contains four subunits, each with an iron-containing heme group that can bind one oxygen molecule. The cooperative binding mechanism allows hemoglobin to efficiently pick up oxygen in the lungs and release it in tissues.
🔬 Key Structural Features
Four polypeptide chains (2α, 2β globins)
Four heme groups with iron centers
Quaternary protein structure
Cooperative oxygen binding (sigmoid curve)
Allosteric regulation by pH, CO₂, 2,3-BPG
Incredible Fact!
Each hemoglobin molecule can carry 4 oxygen molecules, and each red blood cell contains about 280 million hemoglobin molecules - that's over 1 billion oxygen molecules per cell!
🎯 Learning Objectives
Understand hemoglobin's quaternary structure, the role of heme groups, and how cooperative binding enhances oxygen transport efficiency.