lec 1a - Lecture 2 Chemical Foundations I Life occurs in a...

Info icon This preview shows pages 1–22. Sign up to view the full content.

Lecture 2: Chemical Foundations I
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Biomolecules can be classified as: Hydrophilic Hydrophobic Amphipathic Life occurs in a watery environment sugars fats phospholipids
Image of page 2
Atomic bonds and molecular interactions Covalent bonds : strong bonds, small distance between atoms Noncovalent interactions : weaker, larger distance
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Covalent bonds
Image of page 4
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 6
Polar/nonpolar bonds Nonpolar: C-C, C-H Polar: O-H, C-O, N-H, P- O, …. O H C H
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Polar bonds: resonance hybrid H 3 PO 4
Image of page 8
Water is a polar molecule = electric dipole
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Covalent bonds >> noncovalent interactions !! in water !!
Image of page 10
Phosphoanhydre bonds of ATP Free energy ( G o’ ) for hydrolysis = -7.3 kcal
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Covalent bonds >> noncovalent interactions !! in water !!
Image of page 12
Single noncovalent interactions are unstable at 25-37 o C = dynamic!! Multiple noncovalent interactions can create strong and specific associations
Image of page 13

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Ionic interactions Hydrogen bonds Van der Waals interactions Hydrophobic effext Noncovalent interactions:
Image of page 14
Noncovalent interactions: Ionic interactions - + + - + + - - + NaCl + + H 2 0 - strong interaction weak interaction “hydration shell” must be removed for direct interaction with protein
Image of page 15

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Noncovalent interactions: Ionic interactions + long distance electrostatic forces between charges Attraction between anions and cations is diminished by the hydration layers (which keep ions apart) Hydration layers are made of water molecules interacting with ions through weak chemical bonds: + Water molecules tightly bound to ion = hydration layer Water molecules with looser hydrogen bonds with neighbors = move more freely - Electrons from O of water partly shared with cation Hydrogen bond
Image of page 16
Noncovalent interactions: Ionic interactions - + close contact protein-protein: water excluded = strong interaction
Image of page 17

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Hydration shell and selectivity of ion K + channels
Image of page 18
Hydration shell and selectivity of ion K+ channels
Image of page 19

Info icon This preview has intentionally blurred sections. Sign up to view the full version.