Protein Structure & Function Flashcards
Functions of Proteins
- Catalysts
- Transports
- Storage of Molecules
- Mechanical Support
- Generate Movement
- Transmit Signals
Protein molecules adopt a specific
three-dimensional conformation
Native Fold
The 3D structure of a protein that is properly folded and functional
Favorable Interactions in Proteins
- Hydrophobic Effect
- Hydrogen Bonds
- London Dispersion
- Electrostatic Interactions
Hydrophobic Effect
The release of water molecules from the structured solvation layer around the molecule as protein folds increase the net entropy
Hydrogen Bonds
Interaction of N - H and C = O of the peptide bond leads to local regular structures such as alpha helices and
beta sheets
London Dispersion
Medium-range weak attraction between all atoms contributes significantly to the stability in the interior of the protein
Electrostatic Interations
Long-range strong interactions between permanently charged groups
Four Levels of Protein Structure
Primary
Secondary
Tertiary
Quaternary
Amino Acid Structure
Amino Group (NH3+)
Carboxyl Group (CO2)
Hydrogen
R-Group (Variant)
Nonpolar R groups are found in
Hydrophobic amino acids
Neutral R Groups are found in
Polar amino acids
Positively charged R groups are found at
Physiological pH
Negatively charged R groups are found at
physiological pH
*Ex. of Hydrophobic amino acids
Glycine
Alanine
Leucine
Valine
Ex. of Polar amino acids
Threonine
Tyrosine
Glutamine
Serine
Ex. of Positively Charged Amino Acids
Lysine
Arginine
Histidine
Ex. Negatively Charged Amino Acids
Aspartate
Glutamate
Resonance hybrid of two canonical structures
Peptide bond
Resonance causes the peptide bone
- less reactive than esters
- quite rigid and nearly planar
- exhibit large dipole moment in the favored trans config.
