1. Lecture 5 Web: pollev.com/ucibio Text: To: 37607 Type in: 169964

2. OK. What does this all have to do with enzymes? Anfinsen’s experiment Took a protein (AP) & forced it to unfold - Protein lost activity Therefore:______________________________ Allowed protein to recover - Over time, activity returned Therefore:______________________________

3. What does a protein need in order to fold? Protein folding information contained in primary amino acid sequence! OK. But how does amino acid sequence “fold?”

4. Peptide bond is planar…

5. …but not bonds on either side!

6. Rotation of bonds around peptide bond

7. Peptide backbone rotation

8. “Folding” proteins Amino acids have different properties Different preferred Psi and Phi angles Bonds can rotate and pivot

9. Secondary structure 3D structure H-bonds between C=O & N-H C=O & N-H of peptide bonds Close together in primary structure

10. Folding into secondary structures Bond rotation causes secondary structure  -helix  -sheet Bends, Loops, Disordered

11. The  -helix: Annotate Different parameters define  -helix

12.  -Sheet: Annotate

13.  -Sheets Sheets can be twisted

14. Bends / Loops Bends or Loops: Important Structured/Unstructured

15. Tertiary structrue Bring secondary structure elements together Hydrophobic interactions important Unstructured regions important

16. The  -helix Arrangement of side chains important

17. Tertiary structure

18. Tertiary structrue Take picture Upload to Dropbox assignment “Barrel structure”