AOD-9604

AOD-9604 is a 16-residue peptide corresponding to residues 177 to 191 of the growth hormone polypeptide with a tyrosine appended at the N-terminus. The parent 176-191 region is the C-terminal fragment of the hormone, and the added tyrosine was introduced in the originating work to facilitate radioiodination for tracer studies, then retained in the sequence as characterised.

The fragment carries the intramolecular disulfide bridge present in the corresponding region of the intact hormone, forming a small loop. That loop is structurally required: the reduced linear form is reported as inactive in the assay systems used, which makes disulfide integrity a functional attribute rather than a purity detail.

The defining claim in the literature is that this fragment reproduces lipolytic activity attributed to the intact hormone while lacking the growth-promoting and insulin-antagonising activity of the full-length molecule, which depends on receptor-binding determinants that lie outside residues 176 to 191.

Isolated adipocyte preparations, both rodent and cultured, form the core of the in-vitro work, with glycerol release as the standard readout for lipolytic signalling. Reported mechanistic investigation has centred on beta-3 adrenergic receptor expression and on interaction with the lipolytic cascade rather than on the growth hormone receptor itself, since the fragment does not engage that receptor in the reported systems.

Reversed-phase HPLC establishes purity and mass spectrometry confirms identity, reported per lot on the Certificate of Analysis. Because the molecule is cysteine-containing, disulfide status is the release attribute that matters most: the reduced form differs by two daltons and is straightforward to overlook, while intermolecular disulfide-linked dimers are a distinct and separately detectable failure mode.

Non-reducing peptide mapping distinguishes correctly bridged material from reduced and scrambled variants. The N-terminal tyrosine also merits attention, since a deletion sequence lacking it is a plausible synthesis by-product and corresponds to the unmodified 176-191 fragment rather than to this molecule.