Membrane Proteins Flashcards
Describe the beta-pleated sheet structure in proteins
Hydrogen bonds from between each sequential C=O and N-H groups of different parts of the strand
Describe the structure of alpha helices
Every C=O links up with every N-H group every 3.6 amino acid residues
Involvement of R groups in stabilizing alpha helices
None
Name the peptide chains that link the alpha helices and beta pleated sheets
Loop regions
What loop regions come in contact with
The solvent environment
Number of amino acids usually found in the sharp 180 degree turns connecting anti-parallel beta pleated sheets
Usually four
Kinds of tertiary protein structures formed by b-Domain structures
Barrels and saddles
How a barrel structure is formed
Flat staggered sheet (H-bonds higher up on one chain associate with parts lower down on another chain)
How a saddle structure is formed
Flat rectangular (H-bonds line up on the same spots on the chains)
Main domains in NADH:ubiquinone oxidoreductase and each of their functions
- Reaction centre: taking electrons from NADH
- Ubiquinone binding domain: binding ubiquinone, reducing it, then releasing it
- H+ channel: moving protons across the membrane into the intermembrane space
Size, composition and weight of NADH:ubiquinone oxidoreductase
Very large, 536kDa, 16 different protein subunits, 64 membrane helices, 9 Fe-S sulphur clusters, quaternary protein arrangement, UQ binding domain, H+ channel
Equation of NADH oxidation
NAD+ +2H+ + 2e- -> NADH + H+
Equation of ubiquinone reduction
CoQH + H+ + e- -> CoQH2
How electrons are transferred in the NADH reaction centre
Iron ions are used (Fe3+ / Fe2+) in haemoglobin molecules to transfer electrons to molecules with higher electron affinities
How the H+ channel works
There are four subunits, conformational changes generate conditions for movement, as well as a series of ionisation / de-ionisation reactions. Flipping between glutamate and lysine residues.
