Drug Discovery and Development

Molecular Biology in Drug Discovery

  • Definition: The study of biological macromolecules, their reactions, and interactions, particularly in relation to genetics (DNA, RNA) and gene expression control.

Central Dogma of Molecular Biology

  • CDNA
    • F1
  • CRNA
  • Processes:
    • Transcription: DNA to RNA
    • Translation: RNA to Protein

Useful Molecular Biology Techniques

  • DNA sequencing
  • Gene cloning and identification
  • Protein over-expression
  • Gene expression studies
  • Gene knock-out/knock-down methods
  • Protein structure determination
  • Genomics and proteomics

Omics Approaches

  • Traditional Biochemistry: Focuses on individual proteins and small groups of interacting biomolecules, studying kinetics, structure, and cellular roles.
  • Omics: Involves comprehensive study of specific molecules in cells or organisms, demanding experimental and computational resources.

Different 'Omics'

  • Genome: Total genetic content of a cell/organism.
  • Transcriptome: Total mRNA present in a cell/organism.
  • Proteome: Total set of proteins present.
  • Also includes lipidome (lipids), glycome (carbohydrates), metabolome (metabolites).

Genomic Content

  • Complete DNA sequence includes:
    • Protein-coding genes, introns, regulatory sequences, RNA coding sequences, and non-coding "junk DNA".
  • Studied through transcriptomic and proteomic profiling.

Genotype vs. Phenotype

  • Genotype: Genetic constitution inherited from parents.
  • Phenotype: Observable traits resulting from genotype and environmental factors (e.g., brown eyes due to specific gene expression).

Genetic Polymorphisms

  • Variations in DNA sequences among individuals caused by:
    • Chance mutations
    • Induced mutations
    • Viral infections
    • Chemical agents
    • Ionizing radiation

Genetic Disorders

  • Caused by genomic abnormalities, categorized into:
    • Single Gene Mutations: Point mutations, e.g., cystic fibrosis (CFTR) or sickle-cell disease (beta-globin gene).
    • Chromosomal Disorders: Structural/numerical, e.g., Down Syndrome (Trisomy 21).
    • Complex Disorders: Multifactorial, e.g., Alzheimer’s disease, certain cancers.

Mutations and Variations

  • Point Mutations include substitutions (silent, nonsense, missense) and affect protein synthesis.
  • Insertions/Deletions ('InDels') can trouble protein function considerably.
  • Copy Number Variants (CNVs): Include deletions, duplications affecting gene expression.

Genome-Wide Association Studies (GWAS)

  • Collect large datasets linking genetic variations to diseases, establishing correlation but not causation.
  • Useful for diagnosis and prognosis, informing further biological studies.

Transcriptomes & Proteomes

  • Transcriptome: Varies between cell types and conditions; reveals active genes.
  • Proteome: Dependent on post-translational modifications, essential for understanding protein functionality and interactions.

Mass Spectrometry (MS)

  • Key methods for protein analysis, allowing determination of mass, sequencing, and post-translational modifications.
  • Involves ionization of proteins, followed by mass-to-charge ratio measurement.

Drug Discovery Process

  1. Target Identification: Compare healthy vs. disease states, literature searches, and various biological studies.
  2. DNA/Protein Sequencing: Determine the primary sequence of targets.
  3. Structure/Function Elucidation: Understand biochemical and structural characteristics.
  4. Proof of Concept: Develop assays for biological screening.
  5. Lead Structures Selection: Focus high-throughput screening efforts.

Target Identification Techniques

  • Genetic association studies for mutations
  • Gene expression assessments
  • Protein modification investigations

Validation of Drug Targets

  • Ensuring reproducibility and specificity of target interactions.
  • Drug-like molecule modifications are crucial for development.

Recombinant DNA Techniques

  • Enable production of significant amounts of proteins for research.
  • Allow modifications for analysis of ligand-binding trajectories.

Vaccine and Biomarker Applications

  • Identification of vaccine targets and biomarkers through molecular biology methods and 'omics' techniques, linking to personalized medicine efforts.