Sandbox Reserved 431: Difference between revisions

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==Overall Structure==
==Overall Structure==


Cytochrome P450 is an <scene name='48/483888/Cytochrome_p450_dimer/1'>asymmetric dimer</scene>, which means the protein is made of two subunits that are structurally very similar to one another, but not identical. Each dimeric subunit contain 12 α-helices (labeled A-L) along with some β-sheets, which are mostly located on one side of the molecule. Helices F and G from each of the units form the dimer interface of cytochrome P450, and are also involved in the formation of the active site. This dimeric interface of the protein is stabilized by <scene name='48/483888/Cytochrome_p450_interface/1'>hydrogen bonding interactions</scene> between the G helix of one the units with the F helix of the second unit, and vice versa. Two molecules of 2-hydroxypropyl-β-cyclodextrin are also found near the dimer interface. The cyclodextrins are believed to help further stabilize the protein, and also serve to help dissolve and bind vitamin D3. The cyclodextrin molecules also shield the hydrophobic parts of the F and G helices of each subunit from the solvent by <scene name='48/483888/Cytochrome_p450_cyclodextrins/1'>encapsulating the Phe240 residue within its cavity</scene>. Cytochrome P450 has an apparent mass of ~120 kDa.  
Cytochrome P450 exists as an <scene name='48/483888/Cytochrome_p450_dimer/1'>asymmetric dimer</scene>. Each dimeric unit contains 12 α-helices (labeled A-L) along with β-sheets, which are mostly located on one side of the molecule. Helices F and G from each of the two units form the dimeric interface of cytochrome P450, and are also involved in the formation of the active site. This dimeric interface of the protein is stabilized by <scene name='48/483888/Cytochrome_p450_interface/1'>hydrogen bonding interactions</scene> between the G helix of one the units with the F helix of the second unit, and vice versa. Two molecules of 2-hydroxypropyl-β-cyclodextrin, which is used to dissolve vitamin D3, are also found near the dimer interface.  


==Binding Interactions==
==Binding Interactions==
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==Quiz Question 1==
==Quiz Question 1==


(merely an example of what this section might look like)
1A) Why is Proline so poorly suited for inclusion in Alpha Helices?
    A) It cannot hydrogen bond due to the position of its amide
    B) The residue is incapable of forming the correct phi and psi angles in a helix
    C) The steric hindrance of its sidechain
    D) A and C
    E) All of the above


 
1B) This protein being a dimer, has symmetry between its two large sections, from <scene name='48/483888/Gandfhelices/1'>this orientation</scene> where most of the molecule has been cut away for simplicity, you can see where one half (in green) comes within close proximity of the other half (in blue).  These 2 pairs of helices help hold the dimer together via electrostatic interactions.  If the black residue is Arg, and the white residue is Asp, what is most likely to be on the opposite helix
From <scene name='48/483888/This_orientation/1'>this orientation</scene> can you identify the green, red, and blue parts of the molecule?
        (Arg match, Asp match)
    A) Asp, His
    B) Gly, Val
    C) Met, Lys


==See Also==
==See Also==
Retrieved from "https://proteopedia.org/Sandbox_Reserved_431"