Introduction to Enzymology

Introduction to Enzymology – Study Notes

1. What Is Enzymology?

• Definition: Enzymology is the branch of biochemistry that studies enzymes – the protein (or RNA) catalysts that accelerate biochemical reactions in living cells.
• Scope:
  • Enzyme structure & classification
  • Kinetic behavior & mechanisms
  • Regulation & inhibition
  • Methods for purification, assay, and characterization

2. Basic Properties of Enzymes

3. Enzyme Structure

1. Primary structure – linear amino‑acid sequence.
2. Secondary structure – α‑helices, β‑sheets (stabilized by hydrogen bonds).
3. Tertiary structure – overall 3‑D fold; active site formed by residues from different regions.
4. Quaternary structure – assembly of multiple polypeptide subunits (e.g., hemoglobin, α₂β₂).

Key concept: Active site – a pocket/cleft where substrate binds; often contains catalytic residues (e.g., Ser‑His‑Asp triad in serine proteases).

4. Enzyme Classification (IUBMB System)

Mnemonic: Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, Ligases, Translocases.

5. Enzyme Kinetics

5.1 Michaelis–Menten Model

[ v = \frac{V_{\max}[S]}{K_m + [S]} ]

• v – initial reaction velocity
• **V