Lecture 2 - Non-covalent Interactions Flashcards
1
Q
Major types of Interactions
A
- Ionic
- Ion-Dipole
- Dipole-Dipole
- Dipole-induced Dipole
- van der Waal
- H bonds
- Cation - pi
- Desolvation & Hydrophobic effect
2
Q
Ionic Interaction
A
- Ions solvated by water
- Water excluded in protein binding
- Delta G - 3-10 kcal/mol
Ionic interactions are often pH dependent
3
Q
Dipole - Induced Dipole Interactions
A
- 0.5 - 5 kcal/mol
- charged ions interact with permanent dipoles and induce in other molecules
4
Q
van der Waals Interactions
A
- Optimal distance between any 2 atoms that is favorable
- 0.3 - 0.5 A, 0.5 kcal/mol
5
Q
H Bonding Interactions
A
- Electrostatic Interaction between heteroatoms (N,O) & H bound
- Also called dipole-dipole interaction
6
Q
Where does Vancomycin bind to on gram positive bateria?
A
D-Ala-D-Ala terminus
7
Q
What mutation destroys H-bonds & eliminates binding of Vancomycin?
A
Ester formation. Decreases binding affinity by 1000-fold.
8
Q
Cation-Pi Interactions
A
- Positive charged Species near aromatic Amino Acid
- arenes can bind non-covalently by # of different orientations
9
Q
Hard metals that interact with cation - pi interaction
A
Li+, Na+, K+
10
Q
Soft cation that interacts with cation - pi interaction
A
ammonium cation (NR4+)
