Proteomics Flashcards
What is the Proteome?
Entire set of proteins expressed from a genome
Why the proteome bigger than genome?
Alternative RNA Splicing
Post Translational Modification
What are the two functional groups found in all amino acids?
Amine
Carboxylic Acid
What happens to an amino acid when it is in aqueous solution?
NH2 gains a hydrogen to become NH3+
COOH loses a hydrogen to become COO-
What are the four classes of amino acids?
Acidic
Basic
Polar
Hydrophobic
What class of amino acids are negatively charged?
Acidic
Describe the characteristics of a basic R group
Positively Charged
Functional group example: -NH2
Example: Lysine
What class of R groups are found at the surface of a protein?
Polar
What constitutes a peptide bond?
C, H, O, N
What is the primary structure of a protein?
Order in which the amino acids are synthesised into the polypeptide
What stabilises secondary structure of the protein?
Hydrogen Bonds
Where does the hydrogen bonding occur between in secondary structure?
N-<em>H</em> has a weak positive charge and C= <em>O</em> has a weak negative charge
What are the three types of secondary structure?
Alpha Helix
Beta Sheets
Turns
Where are the R groups facing in an alpha helix?
Outwards
Where are the R groups sitting in a beta sheet?
Above and Below
What are the two types of beta sheets?
Antiparallel and parallel
If chains run in opposite directions(in respect to N-C polarity) what type of beta sheet is it?
Antiparallel
What causes tertiary structure?
Interactions between R groups of amino acids
State some possible interactions between R groups
Ionic Bonds
Van der Waals
Disulphide Bridges
What is special about the R groups that are connected with disulphide bridges?
R groups contain sulphur
How does temperature affect the proteins?
- Tertiary structure is destabilised, leading to denaturation
- Increased heat = more kinetic energy, polypeptide chain shakes more
- Weaker interactions such as H bonds are broken
How does pH affect the proteins?
Effects ionisation of the acidic and basic R groups
Changes the charge, so they no longer bond correctly
Polypeptide Unfolds