C12 Lecture 4

Primary structure

Protein's amino acid sequence
Secondary structure

Local spatial arrangement of a polypeptide's backbone atoms
Does secondary structure consider side chains of a polypeptide?

No
Tertiary structure

3D structure of the entire chain
Quaternary structure

Spatial arrangement of different polypeptides in a protein
Do all proteins have quaternary structure?

No.

Some proteins are functional alone in their tertiary form.
How many amino acids in human Hgb α and β strands?

How is this relevant to Hgb separation by SDS-Page?

α: 142 a.a.

β: 147 a.a.

The chains are difficult to separate by weight (SDS-Page)
3D Hgb structure (1-4^o)
- 1^o: KAHGKKVLGA (62-71)
- 2^o: alpha helix
- 3^o: One complete protein chain (beta chain of Hgb)
- 4^o: Four separate chains of Hgb assembled into an oligomeric protein
Space filling model
- Sphere = atom
- Shows the surface exposed to solvent and ligands
Ball and stick model

Excellent for bonding arrangement
Backbone model

Excludes sidechains

Shows general course of polypeptide chains
Cartoon ribbon diagram
- Most common
- Easy to visualize 3D shape
- Can see interior
- Can see folds and patterns
- Can add ball and stick portions
How are proteins represented in a ribbon diagram

alpha helices: coils/thick tubes

beta strand: arrows

lines or thin tubes: random coils

Author

Anonymous

49092

Card Set

C12 Lecture 4

Description

C12 Lecture 4

Updated

2010-11-12T07:37:06Z

Show Answers