Protein structure

What is the primary structure (1$^{o}$) of a protein?

The amino acid sequence of a polypeptide chain

• For example, Leucine-Valine-Glutamic acid

What is the secondary structure (2$^{o}$) of a protein?

The folding pattern of a polypeptide chain

• Two main types:
  1. $\alpha$-helix
  2. $\beta$-pleated sheet
• Mediated by hydrogen bonds