Lipid Proteins Flashcards
Lipid
Any molecule that’s soluble in an organic solvent. Molecules formed by linking a long-chain fatty acid to a glycerol-3- phosphate backbone.
Categories of Lipids
- Quinones
- Fatty acids
- Tricylglycerols
- Cholesterol
- Steroids
- Non-polar vitamins
The glycerol phosphate backbone
Helps form the head of the glycerophospholipid
Shape of membrane amphipathic lipids
Cylindrical in shape -> kinks induced by double bond
3 common fatty acids
Stearic, Oleic, Linoleic
Amphiphilic lipids in water
- Interaction with heads maximised
- Interaction with tails minimised
- Interaction between tails maximised to exclude water
Types of membrane proteins
- Integral
- Peripheral (interact with surface of bilayer/integral membrane protein?
- Lipid anchored
Approximate distance across membrane
40-50 Angstroms
What problem are transmembrane proteins faced with?
Membrane environment -> almost completely non-polar
How do proteins solve transmembrane problem?
- Side chain of transmembrane sections of proteins = hydrophobic so can be acomodated in membrane
- Polar backbone carbonyl + amide groups can’t make favourable interactions with hydrophobic membrane components
- Strong driving force for bonding
What structures are favoured in the hydrophobic membrane?
- Alpha-helical
2. Beta-sheets
Why is it possible for single helices to exist in the membrane?
H-bonds stronger in non-polar environment
Number of membrane-spanning alpha-helices
20-22
How do ligand bound in structural proteins contribute to tensile strength?
Triple helices create regular hydrophobic regions allowing self association. Bundles of triple helices can align to form excessively strong structures.
