What is Kisspeptin-10?
The molecular reference records the sequence H-Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH2 across 10 residues. The carboxy terminal Arg-Phe-amide motif places it in the RFamide family, and that terminus must remain intact for receptor engagement, which makes carboxypeptidase susceptibility the main stability question here. The chain also carries a tryptophan, making it photosensitive.
Kisspeptin-10 is the shortest active fragment of kisspeptin, the peptide encoded by the KISS1 gene, and acts at KISS1R, a G protein coupled receptor also known as GPR54. In rodent and cell model work it is used to study upstream control of gonadotropin releasing hormone neurons, and loss of function in the receptor produces a well characterised reproductive phenotype in mouse models (Seminara, 2003). The same gene product was first described in a metastasis suppression context, which is where the synonym metastin comes from.
What is not settled is how the several naturally occurring fragment lengths differ functionally, how rapidly desensitization develops under continuous versus pulsatile exposure in cell systems, and how much of the metastasis literature reflects the same pathway.
Reconstitution & handling
Sterile or bacteriostatic water is added slowly down the vial wall with gentle swirling. The sequence is only moderately soluble in plain water because of its aromatic content, so the cake is sometimes wetted with a small volume of dilute aqueous ammonia or mildly basic buffer before making up to volume. Concentration is straightforward arithmetic, so 1 mL added to a 5 mg vial gives 5 mg per millilitre.
Storage & stability
Sealed lyophilized vials are held at -20 °C, protected from light and moisture, and brought to room temperature before opening. Light protection matters more than average here because of the tryptophan, so reconstituted solution is kept in amber or foil wrapped vials, refrigerated at 2 to 8 °C, aliquoted for single use, and protected from repeated freezing and thawing. The asparagine residues deaminate slowly in warm aqueous storage, which appears as closely eluting charge variants.
How it's tested
Each lot is analysed by reversed phase HPLC at 214 and 220 nm and reported at 99 percent or greater main peak area, with the tryptophan and tyrosine giving a confirmatory signal at 280 nm. Mass spectrometry verifies identity against the theoretical average mass of 1302.47 derived from C63H83N17O14 and confirms the carboxy terminal amide, since a free acid variant differs by one mass unit and is inactive at the receptor.