Peptide Hormones

Start from the sequence and its modifications. These peptides carry the features that make hormone synthesis hard: intramolecular disulfides that must be formed regioselectively after chain assembly (vasopressin’s 1–6 ring, somatostatin’s 3–14, calcitonin’s 1–7, amylin’s 2–7), C-terminal amides, and — in ghrelin’s case — an O-octanoyl ester on Ser3, the only such acylation among human hormones and the purity-defining step in its manufacture. Solid-phase synthesis builds the chain; the chemistry that matters is in the folding, oxidation, and side-chain handling that follow.

The native hormone is usually a bad drug, and the engineering is the story. Somatostatin lasts only minutes, so the usable medicine is octreotide — the 14-mer distilled to a protease-resistant 8-residue cyclic analog with D-amino acids. Human amylin aggregates into islet amyloid, so pramlintide swaps three residues to prolines that break the β-sheet and make the peptide synthesizable and shelf-stable. Vasopressin becomes desmopressin through a D-arginine and a deamination that split its two receptor activities. ACTH’s whole activity lives in its first 24 residues, so cosyntropin is just that fragment. Each is a distinct design tactic — minimization, anti-aggregation substitution, stereochemical editing, truncation — and reading them together is a short course in peptide drug design.

Provenance and purity are the throughline this catalog exists to track. Several of these (secretin, calcitonin, ACTH) were historically animal-extracted and are now defined synthetic products with a certificate of analysis — a shift from variable biological material to a sequence-verified, assayable molecule. For each entry the failure modes are concrete: deletion sequences, disulfide isomers, des-acyl by-product, aggregation. That is the layer AmericanPeptide.com adds on top of the biology — what it takes to make one of these correctly and prove it.