Practice Problem 1
Use the structures of the following amino acids in the table of standard amino acids to classify these compounds as either nonpolar/hydrophobic, polar/hydrophilic, negatively charged/hydrophilic, or positively charged/hydrophilic.
(a) Valine: R = -CH(CH3)2
(b) Serine: R = -CH2OH
(c) Aspartic acid: R = -CH2CO2-
(d) Lysine: R = -(CH2)4NH3+
(a) Valine is a nonpolar, hydrophobic amino acid.
(b) Serine is a polar, hydrophilic amino acid.
(c) Aspartic acid is a hydrophilic amino acid with a negatively charged R group.
(d) Lysine is a hydrophilic amino acid with a positively charged R group.