1. What is a Peptide? (Biological Foundation)

A peptide is a compound formed by two or more amino acids linked by peptide bonds. It sits right between small-molecule chemical drugs and large-molecule proteins:

Structures within 20-50 amino acids are generally termed peptides.

When the chain exceeds 50 amino acids and develops a complex 3D spatial structure, it is classified as a protein.

In the human body, peptides act as "messengers," regulating metabolism, immunity, and hormone secretion by binding to specific cellular receptors.

2. Peptides vs. Amino Acids vs. Proteins

3. Breakthrough Medical Applications of Peptides

Metabolic Diseases & Weight Loss: GLP-1 receptor agonists like Semaglutide and Tirzepatide mimic natural incretins to suppress appetite, revolutionizing obesity treatment.

Targeted Cancer Therapy (PDCs): Peptide-Drug Conjugates (PDCs) act as a "GPS guide," delivering high-toxicity chemotherapy directly into cancer cells, reducing damage to healthy tissues.

4. Peptides in Cosmeceuticals: The Gold Standard of Anti-Aging

Signal Peptides (e.g., Palmitoyl Pentapeptide-4): Stimulate fibroblasts to accelerate collagen and elastin synthesis, smoothing static wrinkles.

Neurotransmitter-Inhibiting Peptides (e.g., Argireline): Known as "topical Botox," it relaxes facial muscles to significantly reduce expression lines.

Carrier Peptides (e.g., Copper Peptide / GHK-Cu): Delivers vital trace elements to deep skin layers, offering robust antioxidant protection and skin barrier repair.