Description
PrymaLab · Research Use Only
KissPeptin-10 5mg
About 3.8 micromoles · The vial where bacteriostatic water is the wrong first answer
A kisspeptin-10 5mg vial holds about 3.8 micromoles of Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe with an amidated C terminus. Four of those ten residues are hydrophobic and only one is strongly basic, which makes this one of the few articles in this catalogue where the diluent has to be chosen before the vial is opened rather than assumed.
Specification Table
| Property | Value |
|---|---|
| Compound | Kisspeptin-10, human |
| Also called | KP-10, and metastin 45-54 |
| Nominal fill | 5 mg |
| Molecular weight, human | 1302.46 g/mol |
| Molar content | Approximately 3.8 µmol |
| CAS | 374675-21-5 |
| Sequence, human | Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH2 |
| Molecular formula, human | C63H83N17O14 |
| C terminus | Amidated. An RF-amide in the human form |
| Hydrophobic residues | Four of ten: tryptophan, two phenylalanines and a leucine |
| Strongly basic residues | One. A single arginine |
| Practical consequence | Poor solubility in plain aqueous buffer at neutral pH |
| Reported approaches | Dissolution in a small volume of DMSO or of dilute aqueous ammonia first, then dilution |
| Chromophore present | Yes. Tryptophan and tyrosine, so 280 nm absorbance can be used for concentration |
| Storage, lyophilised | -20°C, sealed, dark and dry |
| Storage, reconstituted | -20°C in single-use aliquots. Avoid repeated freeze and thaw |
| Regulatory status | No approved human or veterinary formulation is supplied here |
Why Does Kisspeptin-10 Not Dissolve in Plain Water?
Count the residues in a kisspeptin-10 5mg vial. Tyrosine, asparagine, tryptophan, asparagine, serine, phenylalanine, glycine, leucine, arginine, phenylalanine.
Four of those ten are hydrophobic in the ordinary sense, and one of them is tryptophan, which is the largest and least polar residue there is.
Against that there is a single arginine and the amidated C terminus, so at neutral pH the molecule carries very little net charge to keep it solvated.
A peptide with that composition behaves less like a small soluble hormone and more like a short hydrophobic sequence, which is exactly what it is.
Run bacteriostatic water down the wall of the vial and you get a cake that partly disperses and partly sits there, and a solution whose concentration is whatever went in rather than whatever is dissolved.
The concentration you calculated is then wrong by an amount nobody measured.
What Should It Be Dissolved In?
Something that gets a kisspeptin-10 5mg cake into solution before water is asked to keep it there.
The approaches reported in the literature for hydrophobic peptides of this type are a small volume of dimethyl sulfoxide first, or a small volume of dilute aqueous ammonia, followed by dilution into the working buffer.
Which one is right depends on what the assay tolerates. DMSO at a fraction of a percent is acceptable in most cell work and unacceptable in some. Dilute base raises pH transiently and some assays care.
What I would not do is guess, and what I would not do is add the full working volume of water and hope.
The practical sequence is: dissolve in the smallest volume of the chosen solvent that produces a clear solution, confirm it is clear by eye against a light, then dilute.
Confirm the concentration afterwards rather than assuming it. This peptide has a tryptophan and a tyrosine, so ultraviolet absorbance at 280 nanometres gives a real measurement rather than a calculated one.
Why Is 280 Nanometres Useful Here?
Because most of this catalogue cannot use it and a kisspeptin-10 5mg preparation can.
Absorbance at 280 nanometres depends on tryptophan, tyrosine and cystine. A peptide with none of those has no chromophore, and concentration has to be inferred from the mass someone weighed out.
The bioregulator pages in this catalogue say exactly that, because tripeptides of glutamate and aspartate are invisible at 280.
Kisspeptin-10 has one tryptophan and one tyrosine, which is enough for a usable extinction coefficient.
So on this compound you can dissolve, measure, and find out whether the dissolution worked, which closes the loop the previous section opens.
That is a genuine analytical advantage and it is the reason the solubility problem is annoying rather than serious.
What Does a Kisspeptin-10 5mg Vial Support?
A kisspeptin-10 5mg vial is about 3.8 micromoles, modest by the standards of this catalogue and still large for the work.
Dissolved and diluted to 1 millimolar it gives 3.8 millilitres of stock.
Published in vitro work at the kisspeptin receptor runs at nanomolar, so that stock is the top of a long dilution series rather than anything used directly.
The 10mg fill in this catalogue is the parent page and holds twice this. Neither is limiting for plate work.
Where the smaller fill earns its place is on a compound with a solubility problem, because a failed reconstitution wastes half as much.
That is the honest case for buying this size, and it is a case about your first attempt rather than about the chemistry.
What Should the Certificate Show?
A kisspeptin-10 5mg certificate should carry the full ten residue sequence, written out, with the amidated C terminus stated.
Which species variant it is. The human sequence ends in phenylalanine and the rat and mouse sequence ends in tyrosine, sixteen daltons heavier, and the parent 10mg page in this catalogue covers why that confusion persists.
Observed mass against a calculated 1302.46 for the human form.
Purity by chromatography, with the chromatographic method named on the document.
Net peptide content, which on a peptide with one arginine and TFA from purification is not a small correction.
Lot number and manufacturing date.
What Goes Wrong Most Often?
Somebody reconstitutes a kisspeptin-10 5mg cake into water, gets a cloudy vial, adds more water, and proceeds.
That is the failure I would expect and it produces a concentration error in an unknown direction of an unknown size.
The second thing is repeated freeze and thaw of a stock, which on a hydrophobic peptide encourages the material to come out of solution and stay out.
Single-use aliquots at minus 20 fix that and cost one afternoon.
The third is assuming the 280 nanometre reading of a partly dissolved solution is a concentration. It is a concentration of what dissolved, which is the point, but only if the reading is taken after the solution has been clarified rather than while it is still cloudy.
Turbidity scatters light and inflates apparent absorbance, so a cloudy sample reads high.
A fourth, less common but worse: somebody dissolves in neat DMSO, stores the stock that way, and finds months later that the DMSO has taken up water from the air.
Dimethyl sulfoxide is strongly hygroscopic. A stock left in a partly used bottle changes composition, and a peptide that needed the organic solvent to dissolve will start coming out as the water fraction rises.
Keep the DMSO volume small, dilute promptly into the working buffer, and do not rely on a DMSO stock as a long-term store.
A dated bottle of anhydrous DMSO, opened rarely, is worth keeping separately from the one on the bench that everybody uses. The bench bottle has been open all year.
What Does the Amide at the End Contribute?
A charge that is not there, which is part of why the solubility is what it is.
A free C-terminal carboxyl carries a negative charge at neutral pH. Amidating it removes that charge.
On a peptide with a single arginine and two acidic-adjacent asparagines, losing the terminal negative charge means losing one of the few things keeping the molecule solvated.
The amide is there because it is what the endogenous peptide has, and because the RF-amide motif is characteristic of this family. Removing it to improve solubility would produce a different compound.
So the solubility problem is not a formulation defect. It is the molecule doing what its sequence says it should, and the answer is a better diluent rather than a better peptide.
What Does the Sequence Say About Storage?
Tryptophan first, because it is the residue that dictates the handling.
Tryptophan absorbs ultraviolet light and photodegrades, producing a mixture of oxidation products that a purity trace may or may not resolve. Dark storage is the whole mitigation and it is cheap.
The two asparagines are the slower liability. Asparagine deamidates to aspartate, faster when followed by a glycine, and position seven in this sequence is a glycine.
So Asn-Gly at positions four and seven is a deamidation-prone motif sitting in the middle of the molecule, and in solution at neutral pH it will run.
That is another argument for making solutions fresh and freezing what you do not use, rather than keeping a refrigerated stock for weeks.
How Should the Vial Be Handled?
Handle a kisspeptin-10 5mg vial with the diluent decided in advance.
Store it sealed at minus 20 degrees Celsius, kept dark and dry, because the tryptophan is photosensitive.
Room temperature before opening.
Add the chosen solvent in a small volume first, and give it time and gentle rotation rather than shaking. Shaking a hydrophobic peptide produces foam and foam is where it denatures.
Check it is clear before diluting. Then dilute, then measure at 280 nanometres.
Aliquot into single-use volumes and freeze at minus 20. This is one of the compounds where freezing the solution is right, because the alternative is repeated warming of a peptide that would rather not be in water in the first place.
Published Literature
Full citations for the work named above. The receptor pharmacology references describe the compound rather than this fill, and nothing published addresses fill size.
- Kotani M, Detheux M, Vandenbogaerde A, Communi D, Vanderwinden JM, Le Poul E, et al. Journal of Biological Chemistry. 2001;276(37):34631-34636. DOI: 10.1074/jbc.M104847200
- Kirby HR, Maguire JJ, Colledge WH, Davenport AP. Pharmacological Reviews. 2010;62(4):565-578. DOI: 10.1124/pr.110.002774
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Pharmaceutical Research. 2010;27(4):544-575. DOI: 10.1007/s11095-009-0045-6
Frequently Asked Questions
What is a KissPeptin-10 5mg vial?
A lyophilised research vial holding 5 milligrams of human kisspeptin-10, about 3.8 micromoles at 1302.46 g/mol. The sequence is Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe with an amidated C terminus. It is sold for laboratory research alone.
Does kisspeptin-10 dissolve in bacteriostatic water?
Not cleanly. Four of the ten residues are hydrophobic, including a tryptophan, and there is only one strongly basic residue, so the molecule carries little net charge at neutral pH. Plain aqueous buffer typically leaves a partly dispersed cake.
What should kisspeptin-10 be dissolved in?
A small volume of dimethyl sulfoxide, or of dilute aqueous ammonia, followed by dilution into the working buffer. Which is appropriate depends on what the assay tolerates. Dissolve in the smallest volume that gives a clear solution, then dilute.
How do I confirm the concentration?
Ultraviolet absorbance at 280 nanometres. The sequence contains one tryptophan and one tyrosine, so it has a usable extinction coefficient. Take the reading after the solution is clear, because turbidity scatters light and inflates apparent absorbance.
Why can most peptides here not be measured at 280?
Because absorbance at 280 nanometres depends on tryptophan, tyrosine or cystine, and most of the short bioregulator peptides in this catalogue contain none of them. Kisspeptin-10 is one of the articles where the measurement is available.
How many micromoles are in the vial?
About 3.8, taking the molecular weight as 1302.46 g/mol. Diluted to 1 millimolar that gives 3.8 millilitres of stock, which is the top of a long dilution series for nanomolar in vitro work.
Which species variant is it?
The human sequence, which ends in phenylalanine. The rat and mouse sequence ends in tyrosine and is about sixteen daltons heavier. The certificate should say which, and the 10mg page in this catalogue covers why the two get confused.
Should I freeze the solution?
Yes, in single-use aliquots at minus 20 degrees. This is one of the few compounds here where freezing is the right call, because the alternative is repeatedly warming a hydrophobic peptide that is reluctant to stay in solution.
What should a kisspeptin-10 5mg certificate of analysis show?
The ten residue sequence with the amidated C terminus stated, the species variant, observed mass against a calculated 1302.46 for the human form, chromatographic purity with the method, net peptide content, and lot details.
Why is net peptide content significant here?
Because a peptide purified by reverse phase carries counterion from the mobile phase, and with an arginine present the correction is not small. The mass on the label includes that counterion and residual water.
Is 5mg or 10mg the better purchase?
For a first attempt, 5mg, because a failed reconstitution on a compound with a solubility problem wastes half as much. Neither fill is limiting for in vitro work once the dissolution is working.
Is this product for human use?
No. Laboratory research material, and only that. It is not a drug, food, cosmetic or dietary product, the FDA has not evaluated it, and it is not to be given to a person or an animal under any circumstances.
Compliance Statement
KissPeptin-10 5mg is supplied exclusively for laboratory research use. It is not a drug, food, cosmetic or dietary product of any kind. It has not been evaluated by the FDA or any comparable authority, and no approved human or veterinary formulation is supplied here. It is not intended to diagnose, treat, cure or prevent any disease, and it must not be given to humans or animals. Purchase is restricted to qualified researchers and institutions.
Other formats of KissPeptin-10
KissPeptin-10 is also stocked as Kisspeptin-10 10mg Nasal Spray, Kisspeptin-10 10mg preloaded 3ml pen and KissPeptin-10 (10mg). Each listing states its own quantity and concentration, and the pen and vial comparison explains what changes between formats.
19 reviews for KissPeptin-10 5mg