The flashcards below were created by user
on FreezingBlue Flashcards.
Nonpolar amino acids
Polar uncharged amino acids
Polar charged amino acids
Frequency of nonpolar residues?
Frequency of polar uncharged residues
Frequency of polar charged residue
Top three most common amino acids
- 1. Leucine
- 2. Alanine
- 3. Glycine
Three least common amino acids
- 1. Tryptophan
- 2. Cysteine
- 3. Histidine
Aliphatic residues are more or less frequent?
Much more frequent
Sulfur containing residues are more or less frequent?
Aromatic residues are more or less frequent?
How are amino acids classified?
According to the physiochemical properties of their R-group (especially polarity)
Magnitude of the dipole induced in the presence of an external electromagnetic field
How is molecular polarity approximated in amino acids?
Using the fraction of polar bonds
Two residues having multiple forms at neutral pH
- Cysteine (-SH or -C-S-S-C-)
- Histidine (pKa close to 7, polar or polar charged)
Residues with intermediate polarity
- Glycine - Small R-group, charged proton
- Tyrosine - Polar OH on large aromatic ring
Lacking affinity for water or inability to dissolve
What types of residue tend to be hydrophobic?
Tendency of water to minimize contact with hydrophobic compounds
Why is classification based on hydrophobicity common?
It's easy to measure
How is hydropathy (hydrophobicity) quantified?
Solute partitioning experiments (sep funnel)
Equation for free energy of hydropathy
ΔG = -(RT)ln(Xnp/Xaq)
Formula partition coefficient of hydropathy
K = Xnp/Xaq