Protein Structure and Function
Proteins - (proteios - "first place")
Biological molecules with diverse functions
| Function | |
Example |
| structural | |
beta-keratin (silk: 1SLK) |
| storage | |
albumin (egg white) |
| transport | |
hemoglobin (1ABY, 1HDS) |
| signaling | |
insulin (1ZNI) |
| enzyme | |
amylase (starch -> sugar: 1BAG) |
- Each protein molecule has a specific 3D shape
connected to its function
- Thus, it is important to understand the geometry of
a protein
- But protein molecules are large; many have more than 1000 atoms
- Determine structure by X-ray crystallography (typically 2-3 years
per protein)
Examples:
- Heme, the
molecule in hemoglobin to which oxygen binds
- PFK, a
protein involved in glucose metabolism
- Human cathepsin K, an enzyme involved in breaking down proteins
- Aspirin
and Celecoxib, comparing their effects on two enzymes
Four levels of structure, from fine (small) to gross (large):
- Primary: linear chain of amino acids
- Secondary: alpha helices and beta sheets
- Tertiary: overall global/fibrous shape
- Quaternary: assembly of similar subunits
A Protein DataBank file: thioredoxin.pdb
Examples:
