Myoglobin: Difference between revisions
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[[User:Eric Martz|Eric Martz]] 01:09, 13 September 2014 (IDT) | [[User:Eric Martz|Eric Martz]] 01:09, 13 September 2014 (IDT) | ||
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<StructureSection load='1a6m' size='350' side='right' caption='Structure of Sperm whale myoglobin with O2 and sulfate (PDB entry [[1a6m]])' scene=''> | |||
[[Myoglobin]] is a globular protein whose function is to store molecular oxygen. The fold of the protein is conserved but the sequence is more variable <scene name='23/238129/Conserved_cartoon/1'>conserved</scene>. {{Template:ColorKey_ConSurf}} | |||
The globin consists mostly of [[Helices in Proteins|alpha helices]] shown in <scene name='23/238129/2ndary_structure/2'>pink</scene>; it has no beta sheets and its nonhelical segments mostly serve as links that connect the helices. Look down the barrel of some of the longer helices. Are they all straight? The eight structurally conserved alpha helices are labelled <scene name='23/238129/Helix_labels/1'>A through H</scene>. The protein is colored as a N-->C rainbow in this view; the N terminus is blue, while the C terminus is red. | |||
The heme is shown in spacefilling form with its N, O, and Fe atoms displayed as blue, red, and orange balls. Note how the heme is almost completely enclosed by the globin. Which few chemical groups of the Heme are exposed to the solvent? (holding the mouse over the atoms reveals their identity.) Can you rationalize this exposure? | |||
The heme is shown | |||
View1 is the standard view of Mb. Rotate the protein around to convince yourself that the globin is approximately disc-shaped with a diameter that is about twice its thickness. Turn on the "Main Chain" button to display the polypeptide backbone in white with its N and O atoms represented by blue and red balls. How closely does the ribbon follow the main chain? | View1 is the standard view of Mb. Rotate the protein around to convince yourself that the globin is approximately disc-shaped with a diameter that is about twice its thickness. Turn on the "Main Chain" button to display the polypeptide backbone in white with its N and O atoms represented by blue and red balls. How closely does the ribbon follow the main chain? | ||
Click "Animate" until the Mb ribbon is gray. Turn off the "Mb Ribbon" button. What are the orientations of the main chain carbonyl groups and the amide N atoms relative to each other which allows formation of the H-bonds of the alpha helices (not drawn)? | Click "Animate" until the Mb ribbon is gray. Turn off the "Mb Ribbon" button. What are the orientations of the main chain carbonyl groups and the amide N atoms relative to each other which allows formation of the H-bonds of the alpha helices (not drawn)? | ||
