Session 2 - Protein Stricture and Folding Flashcards
What are the 4 group bound to the central carbon in an amino acid?
Amine group
Carboxyl group
Variable R group
Hydrogen
Define a zwitterion
A molecule that contains an equal number of positively and negatively charged functional groups
What is an amino acid residue?
What remains of an amino acid after it has been joined by a peptide bond to form a protein.
What 8 different classifications for amino acids and what 2 groups do these fit into?
Chemical Properties: - Hydrophobic - hydrophilic - polar - non-polar - acidic - basic Physical Properties: - aliphatic - aromatic
Define what an aromatic and an aliphatic amino acid is
Aromatic - contains a phenyl ring
Aliphatic - only contains carbon and hydrogens
Rotation about 2 bonds in a peptide allow the formation of 3D structures?
Psi (C alpha and C)
Phi (C alpha and N)
Name the key features of a peptide bond and its importance to structure
Peptide bond is planar
Peptides always adopt a trans-structure
Bonds Psi and Phi are free to rotate
Define the isoelectric point of a protein (pI)
The pH at which there is no overall net charge on the protein (pI)
What are the two secondary structures of proteins?
Alpha helix and Beta sheets
Describe the features of an alpha helix
Right handed helix (like that of DNA)
stabilised by H-bonds between N-H and C=O in vertically neighbouring amino acids
Describe the features of a Beta sheet
- composed of adjacent strands
- structure stabilised by H bonds between strands
- commonly Beta strands arranged in antiparallel but can be parallel and mixed arrangements
How does urea affect protein tertiary structure?
Urea is a chaotic denaturant . as such it unravels the tertiary structure by breaking non-covalent bonds
