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Therapeutic Peptides
Therapeutic peptides are short chains of amino acids (usually 2–50 residues) designed to interact with specific biological targets. They can act as hormones, enzyme inhibitors, receptor modulators, antimicrobial agents, or signaling molecules. Their small size allows high specificity, low immunogenicity, and predictable metabolic clearance.
4.1.2 Mechanisms of Action
Hormonal Replacement: Replace or mimic natural hormones (e.g., insulin, calcitonin).
Receptor Modulation: Bind to GPCRs, ion channels, or tyrosine kinase receptors to activate or inhibit signaling (e.g., GLP-1 analogs).
Enzyme Inhibition: Block specific enzymes to regulate pathological pathways (e.g., ACE inhibitory peptides).
Immune Modulation: Act as cytokine mimetics, chemokine inhibitors, or immunostimulatory agents in vaccines and cancer therapy.
4.1.3 Examples
Insulin: glucose regulation.
GLP-1 analogs (liraglutide, semaglutide): type 2 diabetes treatment.
Buserelin, Leuprolide: reproductive disorders and hormone-dependent cancers.
Exenatide: GLP-1 receptor agonist for diabetes.
Antimicrobial peptides: magainins, defensins, experimental infectious disease therapies.
4.1.4 Chemical and Structural Enhancements
PEGylation: increases half-life and reduces immunogenicity.
Cyclization: improves stability against enzymatic degradation.
D-amino acids: resist proteolysis.
Lipidation or carrier conjugation: improves tissue penetration and bioavailability.
Backbone modifications: N-methylation or pseudopeptide bonds enhance stability.
4.1.5 Delivery Strategies
Parenteral: subcutaneous or intravenous injection.
Oral: requires chemical modification to survive GI enzymes.
Transdermal, inhalation, or nasal delivery: experimental approaches.
Nanocarriers and liposomes: protect peptides and target specific tissues.
4.1.6 Challenges
Short half-life due to enzymatic degradation.
Low oral bioavailability.
Potential immunogenicity for non-natural sequences.
High production costs for longer or modified peptides.
4.1.7 Clinical and Emerging Applications
Metabolic disorders: insulin, GLP-1 analogs.
Cardiovascular diseases: ACE inhibitory peptides.
Cancer therapy: peptide vaccines and receptor-targeting peptides.
Infectious diseases: antimicrobial and antiviral peptides.
Neurological disorders: peptides modulating neuroreceptors.
4.1.8 Advantages
High specificity with minimal off-target effects.
Chemically tunable for stability, solubility, and delivery.
Shorter development times compared to full-length proteins.
Therapeutic peptides are short chains of amino acids (usually 2–50 residues) designed to interact with specific biological targets. They can act as hormones, enzyme inhibitors, receptor modulators, antimicrobial agents, or signaling molecules. Their small size allows high specificity, low immunogenicity, and predictable metabolic clearance.
4.1.2 Mechanisms of Action
Hormonal Replacement: Replace or mimic natural hormones (e.g., insulin, calcitonin).
Receptor Modulation: Bind to GPCRs, ion channels, or tyrosine kinase receptors to activate or inhibit signaling (e.g., GLP-1 analogs).
Enzyme Inhibition: Block specific enzymes to regulate pathological pathways (e.g., ACE inhibitory peptides).
Immune Modulation: Act as cytokine mimetics, chemokine inhibitors, or immunostimulatory agents in vaccines and cancer therapy.
4.1.3 Examples
Insulin: glucose regulation.
GLP-1 analogs (liraglutide, semaglutide): type 2 diabetes treatment.
Buserelin, Leuprolide: reproductive disorders and hormone-dependent cancers.
Exenatide: GLP-1 receptor agonist for diabetes.
Antimicrobial peptides: magainins, defensins, experimental infectious disease therapies.
4.1.4 Chemical and Structural Enhancements
PEGylation: increases half-life and reduces immunogenicity.
Cyclization: improves stability against enzymatic degradation.
D-amino acids: resist proteolysis.
Lipidation or carrier conjugation: improves tissue penetration and bioavailability.
Backbone modifications: N-methylation or pseudopeptide bonds enhance stability.
4.1.5 Delivery Strategies
Parenteral: subcutaneous or intravenous injection.
Oral: requires chemical modification to survive GI enzymes.
Transdermal, inhalation, or nasal delivery: experimental approaches.
Nanocarriers and liposomes: protect peptides and target specific tissues.
4.1.6 Challenges
Short half-life due to enzymatic degradation.
Low oral bioavailability.
Potential immunogenicity for non-natural sequences.
High production costs for longer or modified peptides.
4.1.7 Clinical and Emerging Applications
Metabolic disorders: insulin, GLP-1 analogs.
Cardiovascular diseases: ACE inhibitory peptides.
Cancer therapy: peptide vaccines and receptor-targeting peptides.
Infectious diseases: antimicrobial and antiviral peptides.
Neurological disorders: peptides modulating neuroreceptors.
4.1.8 Advantages
High specificity with minimal off-target effects.
Chemically tunable for stability, solubility, and delivery.
Shorter development times compared to full-length proteins.