Protein Structure 2.1
Amino acids are the building blocks of proteins.
Amino acids are linked by peptide bonds to
Protein folding is determined by weak non-covalent interactions among amino acid
fold into higher order secondary structures, which then lead to the tertiary, three-dimensional
fold of the protein.
1. Amino acids. Amino acid side chains confer certain characteristic properties.
2. Peptide bonds. Peptide bonds link amino acids into polypeptide chains.
3. Weak non-covalent bonds. Non-covalent bonds stabilize secondary, tertiary, and quaternary
4. Secondary structures. Protein secondary structures include "-helices, $-sheets, and loops and
5. Tertiary structure. Tertiary structure is determined by x-ray crystallography or NMR.
1. Amino acids have a cen 2
tral carbon atom attached to an amino (-NH ) group, a carboxyl (-COOH)
group, a hydrogen atom, and a side chain (R).
2. Side chain R groups confer characteristic properties:
- basic: Arg, Lys, His
- acidic: Asp, Glu
- polar, uncharged: Asn, Gln, Ser, Thr, Tyr, Cys
- nonpolar: Gly, Ala, Ile, Leu, Val, Phe, Trp, Met, Pro
3. Peptide bonds are amide bonds between amino acids that link the carboxyl group of one amino
with the amino group of the next amino acid.
4. Peptides are drawn with the amino (N) terminus to the left and the carboxyl (C) terminus to
5. Column chromatography is a method to separate/fractionate proteins.
6. Ion exchange chromatography separates proteins by electrostatic interactions (charge)
7. Reverse phase chromatography separates proteins by hydrophobic interactions
8. Gel filtration (molecular exclusion) chromatography separates proteins by size
9. Affinity chromatography separates proteins by specific ligand binding properties