How it works
Somatropin is recombinant human growth hormone produced at the full 191-amino-acid length of the pituitary hormone, distinguishing it from earlier 192-residue preparations carrying an extra N-terminal methionine. A single molecule binds two growth hormone receptors in sequence, and it is that dimerisation — not binding alone — that activates the receptor-associated JAK2 kinase. JAK2 phosphorylates STAT5, which translocates to the nucleus and drives transcription of IGF-1, principally in the liver. Much published work therefore reads growth hormone activity indirectly, through circulating IGF-1 rather than through the hormone itself, whose pulsatile release makes single-timepoint measurement unreliable.
Learn more about the science →Certificate of Analysis+
LC-MS identity, HPLC purity, mass spec confirmation, endotoxin by LAL, appearance. Third-party ISO-17025 verified.
View full certificate →Specifications+
Storage & handling+
Lyophilized: −20°C, protected from light. Reconstituted: 2–8°C. Reconstitute with bacteriostatic water; swirl gently, do not shake — growth hormone is a large protein and agitation denatures it.
We ship in insulated parcels with phase-change cooling and a tamper-evident seal.
FAQs+
Why is this vial measured in IU and not mg?+
Growth hormone has been standardised by biological activity since long before recombinant production made mass measurement straightforward, and the field kept the convention. 36iu is approximately 12mg, but every published protocol and every reference preparation is written in international units, so the vial and this page are too.
What does 191-AA mean?+
The full 191-residue length of pituitary human growth hormone. Earlier recombinant preparations produced in E. coli carried an extra N-terminal methionine, making them 192 residues — a difference detectable by mass spec and relevant to identity work.
Why is a 22 kDa protein in a peptide catalog?+
It sits at the boundary. At 191 residues somatropin is a protein by any conventional cutoff, but it is handled, stored and studied alongside the growth-hormone secretagogues — Sermorelin, Ipamorelin, CJC-1295 — which act upstream of it, so it is catalogued with them.
What identity check matters most?+
Intact mass against 22,124 g/mol. It separates 191-AA from 192-residue material, and it catches the deamidation and disulfide scrambling that a sequence-level check alone would miss.
The research behind this compound, cited in full.
Provided for context only. None of the studies cited below evaluate hábit material specifically; they document the published literature on the compound and its mechanism. Research-use claims are not therapeutic claims.
- [01] Cunningham BC. et al. Science 254 (1991): 821–825.
- [02] Brooks AJ. & Waters MJ. Nat Rev Endocrinol 6 (2010): 515–525.
Verified buyer notes
Initials only — every quote is verified against an order record. We don’t ghost-write reviews.
“COA matched what we ran in-house. Powder reconstituted clean, no haze. Did exactly what we needed it to.”
“Switched after two bad lots from a previous source. Three orders in, zero issues.”
“Asked support a purity question and got the raw HPLC trace back within the hour. That transparency is why we reorder.”