Classification and solid-phase synthesis

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Peptides are classified by several simultaneous criteria:

• By size: oligopeptides (few residues) and polypeptides (long chains); the boundary with "protein" is around 50 amino acids.
• By origin: endogenous (produced by the body, such as GLP-1 or GHRH), synthetic analogs of natural molecules, or newly designed sequences.
• By function: hormonal, neuropeptides, growth factors, repair signaling peptides, antimicrobials, etc.

Solid-phase synthesis (SPPS)

The dominant technique is Merrifield's SPPS (Nobel 1984). The first amino acid is anchored to a resin; the chain grows through cycles of deprotection → coupling → washing, one residue at a time, from the C-terminus to the N-terminus. Two protection chemistries are used: Fmoc (base-labile, the current standard) and Boc (acid-labile, historical). At the end, the peptide is cleaved from the resin, purified by preparative HPLC and its identity confirmed by mass spectrometry.

The great advantage over biological extraction is reproducibility: exactly the same sequence is obtained batch after batch, with characterizable impurities (deletion, truncated and epimerized peptides) that the analytics of Module 7 can quantify.

Educational content for scientific purposes. It distinguishes preclinical from clinical evidence and is not medical advice, diagnosis or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).