BIOCH200 Lecture 3: Protein structure and function: The structure and function of Myoglobin and Haemoglobin
11 Dec 2017
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The structure and function of myoglobin and haemoglobin. Function of a protein is determined by its structure only. Two very important proteins are myoglobin and haemoglobin. Haemoglobin in rbc binds with o2 in the lungs and releases it in the tissues. They both bind reversible to oxygen but with different affinities and conditions. Function of myoglobin: facilitates o2 diffusion through muscle tissue, stores o2 in aquatic animals. Structure of myoglobin: 153 amino acids, heme prosthetic group, globular protein, one polypeptide chain. Also prevents oxidation of the iron atom: distal histidine/ histidine e7 assists o2 binding to heme by increasing affinity and specificity for. O2, and lowering affinity for co. o2 forms hydrogen bond with the distal histidine. Ligand affinity doesn"t change: graph shows binding of o2 to myoglobin (kd, the process is reversible, most of the o2 is released in active muscles.
