Protein 1

Table of Contents
Biomolecules Gateway Page
Jmol Tutorial

In this module:

Amino Acids
Hydrophobic and Polar Amino Acids
Acidic and Basic Amino Acids
Peptide Bonds
Planarity of Peptide Bonds
Protein Sequences
Sickle Cell Anemia

Hydrophobic Amino Acids

What are hydrophobic and polar groups?

Amino acids are grouped according to what their side chains are like. The nine amino acids that have hydrophobic side chains are glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), proline (Pro), phenylalanine (Phe), methionine (Met), and tryptophan (Trp). Shown at the right is the structure of valine. These side chains are composed mostly of carbon and hydrogen, have very small dipole moments, and tend to be repelled from water. This fact has important implications for proteins' tertiary structure (see the Proteins 2 module for a discussion of tertiary structure).

Polar Amino Acids

Six amino acids have side chains that are polar but not charged. These are serine (Ser), threonine (Thr), cysteine (Cys), asparagine (Asn), glutamine (Gln), and tyrosine (Tyr). These amino acids are usually found at the surface of proteins, as discussed in the Proteins 2 module. Shown at the right is the structure of serine.

Hydrophobic and Polar Amino Acids