Intro
- Protein monomer: Amino acid
- All proteins contain nitrogen
- Only proteins contain sulfur – Remember for tests
- Amino acids are neutral (Non-polar and no acidity/basic)
*Amino group is basic and the carboxyl group is acidic – it cancels out
Protein Structure
Proteins are long continuous chains of amino acids with attached R groups. The interactions between these different R groups form different shapes, which in turn make proteins have different functions. A quick picture below shows how a single chain folds into larger molecules.
Protien Folding
Primary Structure
- New bonds always join on carboxylic side
- Amino acid monomers held by covalent peptide bonds
- R groups determine polarity / acidity of the ENITRE monomer (since base amino acid is neutral)
*common examples of R groups below – MEMORIZE
Secondary Structure
- Held by hydrogen bonds
- Alpha helix or beta sheet structure
- Forms between N-H – – – – O=C bond of peptide backbone
Tertiary Structure
- Held by R-Groups within the protein (all bonds here are R groups formed between different peptide bonds)
- Test Tip: The disulfide bond is covalent (meaning it is permanent)
Quaternary Structure
- Held by R groups between different proteins