L2 Protein biochemistry Flashcards
Give me examples of proteins
Proteins are extremely versatile biomolecules
- Hormones
- Antibodies
- DNA binding proteins
- Porin
- Ferritin
- Microtubules
- Enzymes
What are the 4 levels of protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
Describe primary structure
Order of amino acids (residue) in the polypeptide
How are amino acids joined together into polypeptide chains?
Condensation reaction between the N- terminus of one amino acid and the C - terminus of another amino acid forming a peptide bond
Is there flexibility around the peptide bonds?
Rotation is not possible around the peptide bonds - but more flexibility for other bonds
Describe secondary structure
The folding patterns that emerge from the linear sequence of amino acids which are stabilised by hydrogen bonds
Folding patterns are the alpha helix and beta sheet
When forming a helical structure, how far apart does the H-bond need to be?
H- bonds between amino (positive) and carboxyl (negative) groups of amino acids need to be 3 residues in between
Are H bonds closer in beta sheet or alpha helixes?
H bonds are closer in alpha helixes
H bonds are further away from each other in beta sheet
Describe the tertiary structure
- Overall three- dimensional shape of a protein
What are the types of interactions within the tertiary stucture?
Disulfide bridges
Hydrogen bonds
Ionic bonds
Hydrophobic interactions
Van der Waals forces
Describe the quaternary structure
Polypeptides come together to form a more complex structure wih two or more subunits
What is post transitional modification?
They are chemical changes that occur to a protein after its synthesis by ribosomes during the process of protein biosynthesis (translation)
Name me some examples of post translational modifications (PTM)
- Methylation: Adding CH3 groups
- Glycosylation: adding sugars
- Ubiquitination: addition of a 76-aa polypeptide
