Protein Structure Flashcards
Structure of a protein
NH2, C00H and R group
How many amino acids are there
20
R group types
Non-polar aliphatic (hydrophobic)
Aromatic (hydrophobic and carbon ring)
Polar (uncharged and hydrophilic)
+ and - charged (hydrophilic at ph7)
What is the primary structure
Sequence of amino acids linked by peptide bonds
The primary structure is rigid and planar as
The bond has a partial double bond character
Amino acids are folded into shape by
Electrostatic attractions, Hydrogen bonds, Vanderwall’s attractions and disulphide bonds
What is a secondary structure
Beta pleated sheet, alpha helix, beta turns
The beta sheet is either
Antiparallel- one up and one down from C to N and and vice versa
Parallel – hydrogen bonds form between chains
Alpha helix has internal
Hydrogen bonds
Beta turn Connect 
Secondary structures and make a kink in chain of beta sheets or alpha helix
Tertiary structure is
3-D structure of folded protein
The quaternary structure is
Several chains put together e.g. haemoglobin
What is entropy
The measure of disorder
The primary structure determines
The tertiary structure
Proteins from generating a structure with the lowest
Free energy (entropy)
What interactions are important in protein folding
Hydrophobic
What drives folding and maintains the overall structure
Hydrophobic core
What happens when a protein is unfolded
Hydrophobic collapse to form molten globule, internal core rearrangement to form native event
Proteins are folded into multiple
Domains
Domains have a specific function e.g.
DNA binding, spanning plasma membranes
What does chaperones do in protein domains
Guide proteins to fold correctly
What happens in protein denaturation
Solvents that break noncovalent interactions cause the protein to unfold
Some proteins recover and refold
Protein mutations  are
A change in amino acid sequence which alters its tertiary structure and causes inherited disorders eg sickle cell anaemia
What is a signal sequence
A group of an amino acid which determines where the proteins will go (ReR, golgi etc)
If there is no sequence then they will go to the cytosome 
