Real-World Applications of Biomolecule Concepts

1. Enzyme Inhibitors as Drugs

• Aspirin → Irreversibly inhibits COX (cyclooxygenase) → reduces prostaglandin synthesis → anti-inflammatory, antipyretic, antiplatelet
• Statins → Competitive inhibitors of HMG-CoA reductase → reduce cholesterol synthesis
• Penicillin → Irreversible inhibitor of transpeptidase → prevents bacterial cell wall synthesis
• Methotrexate → Competitive inhibitor of dihydrofolate reductase → anti-cancer, anti-rheumatic

2. Enzyme Deficiency Diseases

• Lactose intolerance → Deficiency of lactase → cannot digest lactose → GI symptoms
• Phenylketonuria (PKU) → Deficiency of phenylalanine hydroxylase → phenylalanine accumulates → brain damage
• Glycogen storage diseases → Various enzyme deficiencies in glycogen metabolism (e.g., Von Gierke disease: glucose-6-phosphatase deficiency)

3. Zymogens — Preventing Self-Digestion

• Pepsinogen → Pepsin (activated by HCl in stomach)
• Trypsinogen → Trypsin (activated by enterokinase in small intestine)
• Prothrombin → Thrombin (blood clotting cascade)
• Significance: Prevents self-digestion of enzyme-producing cells and ducts

4. Diagnostic Enzyme Tests

• Elevated ALT/AST (aminotransferases) → Liver damage
• Elevated amylase/lipase → Pancreatitis
• Elevated CK-MB (creatine kinase) → Myocardial infarction
• LDH isoenzymes → Tissue-specific damage markers

5. Cofactor Deficiency Diseases

• Niacin (B3) deficiency → N$AD^{+}$ deficiency → Pellagra (4 Ds: Dermatitis, Diarrhoea, Dementia, Death)
• Riboflavin (B2) deficiency → FAD deficiency → impairs oxidative metabolism