Proteins Flashcards
Protein Structure
Many Polypeptides
Amino Acids
- NH2 = Amine Group
- COOH = Carboxyl Group
- R = chain
- H = Hydrogen
- C = Carbon
Condensation of Amino Acids
A Peptide Bond
Dipeptides
- 2x Amino Acids
Polypeptides
- Several Amino Acids
Hydrogen Bonds
Strongly Polar R Groups
Most Common Bonds
Weakest Bonds
Ionic Bonds
Form between Positively Charged Amine Group and Negatively Charged Carboxylic Acid
Bonds Broken by pH change
Stronger but less Common
Disulfide Bonds/Bridges
Form between two Cysteine R Groups
Strongest but less Common
Broken by Reduction Reaction
Common in secreted Proteins e.g. Insulin
Test for Proteins
- Crush sample + Dissolve in water
- Add Biuret Reagent + Mix
- Positive Result = Blue –> Lilac
Primary Structure
The Sequence of Amino Acids
Bonded by Covalent Peptide Bonds
In a Polypeptide Chain
Secondary Structure
Localised Hydrogen and Ionic Bonding
E.g. Alpha Helicase + Beta Pleated Sheets
Tertiary Structure
More widespread bonding between Amino Acids
- Hydrogen
- Ionic
- Disulphide Bridges
Quaternary Structure
Different Polyeptide Chains make the Protein.