Tertiary and Quaternary structures of proteins

1
Tertiary and Quaternary structures of proteins

• Three dimensional arrangement of all atoms in the
  protein is called tertiary structure.
• Three dimensional arrangement of two or more
  separate peptides in a complex is called
  quaternary structure.

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
Proteins have common structural patterns.

• Supersecondary structures, motifs or folds, are
  particularly stable arrangements of several
  elements of the secondary structure.
  (helix-turn-helix)
• Large proteins (gt300 a.a) may fold into several
  stable globular units called domains
  (transcription factors).

15
(No Transcript)
16
Rules for secondary structure.

• Hydrophobic side groups must be buried inside the
  folds, therefore, layers must be created (b-a-b
  a-a).
• a-helix and b-sheet, if occur together, are found
  in different structural layers.
• Adjacent polypeptide segments are stacked
  together.
• Connections between secondary structures do not
  form knots.
• The b-sheet is the most stable.

17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
Protein denaturation and folding

• Loss of secondary structure called denaturation.
• Denaturation can be accomplished by
• Heat
• pH
• Organic solvents Urea, GuHCl
• Removal of denaturing agents can lead to
  refolding of the secondary structure-renaturation.
  
• Renaturation-proof of the primary structure
  function relationship.

28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)