Part I: Amino Acids & Proteins
The Building Blocks of Life
Proteins are the molecular machines of the cell, performing virtually every biological function from catalysis to structural support. Understanding protein biochemistry begins with the 20 standard amino acids — their structures, chemical properties, and how they combine through peptide bonds to form polypeptide chains. These chains fold into precise three-dimensional structures dictated by the amino acid sequence, enabling specific biological functions.
20
Standard Amino Acids
4 Levels
Protein Structure
~20,000
Human Protein Genes
Lecture Companions: Water, Amino Acids & Protein Structure
A 9-lecture undergraduate primer covering the chemistry of water, the 20 amino acids, and the four levels of protein structure — review before the quantitative chapters below.
Water
1A. Water (Polarity)
1B. Water — Universal Solvent & van der Waals
1C. Water — Acids and Bases
1D. Water — Buffers
Amino Acids
2A. Amino Acids (General)
2B. Amino Acids (Individually)
2C. Amino Acids (Peptide Bonds)
Protein Structure
3A. Primary & Secondary Protein Structure
3B. Tertiary & Quaternary Protein Structure
Topics in This Part
1. Amino Acid Structure & Properties
The 20 standard amino acids, stereochemistry, acid–base properties, pKᴁ values, and the Henderson–Hasselbalch equation
2. Peptide Bonds & Primary Structure
Condensation reactions, peptide bond geometry, partial double-bond character, and primary sequence determination
3. Protein Folding & Higher-Order Structure
Secondary structure (α-helix, β-sheet), tertiary folding, quaternary assembly, and Anfinsen's thermodynamic hypothesis
4. Protein Function: Hemoglobin & Myoglobin
Oxygen binding, cooperative allostery, the Bohr effect, sickle cell disease, and structure–function relationships