Essay Compare And Contrast The Structures Of Myoglobin
Question 1 (4 marks)-
Compare and contrast the structures of myoglobin and hemoglobin. How does each structure relate to its function?
Myoglobin and haemoglobin, are both globular proteins, however, myoglobin is present in the heart and skeletal muscles, while haemoglobin is only found in red blood cells. The function of myoglobin is to bind and release oxygen to the muscle cells, whereas the function of hemoglobin is to transport oxygen from the lungs to the tissues, and transport carbon dioxide from tissues back to the lungs. Although both molecules bind to oxygen, their structures differ. While looking at myoglobin’s structure, it is evident as consisting of one polypeptide chain, and within this chain, 80 % of it is folded into eight alpha – helices . These regions are terminated by beta bends/ loops or proline. The interior is mostly tightly packed nonpolar amino acids, which results in a structure being formed which can be stabilized by hydrophobic interactions between the clusters. On the surface there are polar acids, which can form hydrogen bonds with water and themselves. It has a single heme prosthetic group. It is in a crevice and …show more content…
In regard to hemoglobin, when an oxygen molecule binds with one heme group, the oxygen affinity increases for the other three heme groups on the tetramer. It is more difficult for the first oxygen to bind, however, when the affinity increases, and the partial pressure reaches approximately 20-30 mm Hg, the saturation with oxygen will occur much faster, and will eventually level out, as ligand binding positions become occupied. This causes the sigmoidal shape of its oxygen-dissociation curve. Overall, cooperative binding is essential to hemoglobin, as it allows for oxyhemoglobin to carry its maximum amount of oxygen, while it allows deoxyhemoglobin to release its maximum amount of
Compare and contrast the structures of myoglobin and hemoglobin. How does each structure relate to its function?
Myoglobin and haemoglobin, are both globular proteins, however, myoglobin is present in the heart and skeletal muscles, while haemoglobin is only found in red blood cells. The function of myoglobin is to bind and release oxygen to the muscle cells, whereas the function of hemoglobin is to transport oxygen from the lungs to the tissues, and transport carbon dioxide from tissues back to the lungs. Although both molecules bind to oxygen, their structures differ. While looking at myoglobin’s structure, it is evident as consisting of one polypeptide chain, and within this chain, 80 % of it is folded into eight alpha – helices . These regions are terminated by beta bends/ loops or proline. The interior is mostly tightly packed nonpolar amino acids, which results in a structure being formed which can be stabilized by hydrophobic interactions between the clusters. On the surface there are polar acids, which can form hydrogen bonds with water and themselves. It has a single heme prosthetic group. It is in a crevice and …show more content…
In regard to hemoglobin, when an oxygen molecule binds with one heme group, the oxygen affinity increases for the other three heme groups on the tetramer. It is more difficult for the first oxygen to bind, however, when the affinity increases, and the partial pressure reaches approximately 20-30 mm Hg, the saturation with oxygen will occur much faster, and will eventually level out, as ligand binding positions become occupied. This causes the sigmoidal shape of its oxygen-dissociation curve. Overall, cooperative binding is essential to hemoglobin, as it allows for oxyhemoglobin to carry its maximum amount of oxygen, while it allows deoxyhemoglobin to release its maximum amount of