Protein Structure Flashcards
What is electronegativity?
The relative tendency of an atom to attract electrons to itself when it is covalently bonded with another atom
Name electropostive and electronegative atoms
Electropositive: 1/2valence electrons (K and Na)
Electronegative: have 6/7 valence electrons (O, N, Cl, F)
Features of primary structure
Linear sequence of AA
Sequence confers function
Features of secondary structure
Localized, repetitious folding
Result from hydrogen bonds forming between peptide linkage
Alpha helix and beta pleated sheets
Describe the alpha helix structure
Is generated when a single polispepticle chain turns regularly about itself making a rigid cylinder
Is stabilized by hydrogen bonds
18 AA = 5 -complete turns of the alpha helix
Describe the beta pleated sheets
The polypeptide chain loopsback on itself to lineup side by side
Is stabilized by hydrogen bonds
Strands in the sheet can be parallel (same direction) or antiparallel ( opposite direction)
Describe the tertiary structure
3D conformation of the polypeptide chain
Multiple side chain interactions are involved
Ionic interaction between positive and negative side chains
What is the most common tertiary structure folding pattern?
4 -helix bundle fold eg. Cytochrome b protein
What is an example of a Greek fold pattern?
The bacterial CusF copper binding proteins
Where is the FERM domain fold found?
In proteins interacting with the plasma membrane
What is the TIM barrel fold?
Alternation between the alpha helix and beta pleated sheets, eg. Triose phosphate isomerase
What is the rossmann fold?
Is an arrangement of alpha helix and beta pleated sheets eg. Nucleotide binding proteins
Describe the quartenary structure
2 or more polypeptide chains connected
Name protein misfolding disorders
Cystic fibrosis
Huntington’s disease
Creutzfeldt- Jakob disease
Describe how cystic fibrosis occurs
Gene contains mutation or deletion
Protein is misfolded
Degraded protein
Loss of function
