Proteins Flashcards
What is released when a peptide bond is formed?
Water (and it’s a condensation reaction 🫥)
What is the primary structure of a protein
The sequence of amino acids
What is the secondary structure of a protein?
The spatial arrangement of amino acid residues that are near each other in the linear sequence
What are the two structural forms of the secondary structure?
Alpha helix, beta sheets
What stabilises the alpha helix structure?
H bonds between the NH groups and the CO groups in the next turn of the helix
What stabilises the beta sheets?
H bonds between the amide groups of the linear polypeptide chains
What is the tertiary structure?
The spatial arrangements of amino acids residues that are far apart in the linear sequence/
Results when functional groups of ‘R’ chains of amino acids in the polypeptide chain interact with one another
What is the tertiary structure held together by?
Van der waals forces
Ionic interactions
Hydrogen bonds
Disulphide bridges
Hydrophobic interactions
Where do ionic interactions take place?
Between two oppositely charged R groups
What environment is needed for intra polypeptide hydrophobic interactions to occur?
An environment within proteins from which water is excluded
Where do disulphide bridges occur?
They are strong covalent bonds that occur between two cysteine residues
They are common in extra-cellular proteins
They can occur between as well as within a polypeptide
What is the quaternary structure?
The spatial arrangement of individual polypeptide chains in a multi-subunit protein.
Sometimes several polypeptides interact with one another to form a quaternary structure.
What structure remains in tact after denaturation?
The primary structure
What are common causes of denaturation?
Acids
Heat
Solvents (ethanol)
Cross linking reagents (formaldehyde)
Chaotropic agents (urea)
Disulphide bond reducers (2 mercaptoehanol)
What is the effect of denaturation?
Decrease in solubility
Altered water binding capacity
Loss of biological activity
Improved digestibility
