Lecture 1: Introduction to proteins Flashcards
How many amino acids are commonly found in protiens?
How do these proteins differ?
20 - protiens differ by their R group which gives them different chemical & physical properties
How do you recognise if an amino acid is uncharged polar?
What are some examples?
The amino acid has:
- OH group
- NH2 group
- SH(cya)
e. g Ser, Tyr, Thr, Gln, Asn
How do you recognise if an amino acid is charged polar?
What are some examples?
-ve charge = acidic e.g glutamate and aspartic are -ve charged at physiological pH
+ve charge = basic e.g Histadine, Lysine and Arginine
How do you recognise if an amino acid is non-polar?
What are some examples?
The amino acid has:
- aromatic ring
- CH3 side groups
- S-S disuophide
e. g Ala, Val, Leu, Ille, Gly, Pro, Phe
What is the isoelectric point?
The pI is the pH at which the net charge on an amino acid is zero —-> zwitterion form is most abundant
What are the properties of the peptide, C-N bond?
The C-N bond linkage has partial double bond characteristic due to electron resonance making the peptide:
- Planar, flat - rigid
- no rotation about = bond
- increased orbital overlap
- very stable and rigid
What are some examples of post-translational modifications?
- Phosphorylation
- Formation of disulphide bridges
- Addition of a lipid
- Metal binding
