Description
PrymaLab · Research Use Only
Thymosin Beta-4 Fragment (1-4) (Ac-SDKP)
500mcg per capsule, 60 capsules · Four names, one tetrapeptide, one misleading one
Goralatide is the international nonproprietary name for the tetrapeptide N-acetyl-Ser-Asp-Lys-Pro, more often written Ac-SDKP. Its structure was determined in 1989 from bone marrow, before anyone connected it to thymosin beta-4. That order of discovery is why one of the four names this compound carries describes it accurately and the others describe where it was later found to come from.
Specification Table
| Property | Value |
|---|---|
| Product format | Capsules, 60 per container |
| Content per capsule | 500 µg |
| Total content per container | 30 mg across 60 units |
| Sequence | N-acetyl-Ser-Asp-Lys-Pro, four residues, N-terminally acetylated |
| Molecular formula | C20H33N5O9 |
| Molecular weight | Approximately 487.5 g/mol, calculated from residue masses |
| Molar content per capsule | Approximately 1.03 µmol |
| Molar content per container | Approximately 61.5 µmol |
| International nonproprietary name | Goralatide |
| Other designations | Ac-SDKP · AcSDKP · seraspenide · thymosin beta-4 fragment (1-4) |
| Structure determined | 1989, from bone marrow, by Lenfant and colleagues |
| Endogenous release | From thymosin beta-4 by prolyl oligopeptidase |
| Known enzymatic fate | Hydrolysed by the N-terminal active site of angiotensin converting enzyme |
| CAS | Not stated here. Confirm against the lot certificate rather than against this page |
| Storage | Sealed container, cool, dry and dark |
| Regulatory status | No approved human or veterinary formulation is supplied here |
Why Does Goralatide Have Four Names?
Because goralatide was discovered, named, renamed and then re-described over about fifteen years.
Lenfant and colleagues purified it from bone marrow and determined its structure in 1989. At that point it was a tetrapeptide that inhibited proliferation of haematopoietic stem cells, and the early literature calls it seraspenide.
Goralatide is the international nonproprietary name, which is the formal designation for the substance itself.
Ac-SDKP is not really a name. It is the sequence written in one-letter code with the acetyl group noted, which is how chemists refer to short peptides and which is unambiguous.
Thymosin beta-4 fragment (1-4) came later, and it describes origin rather than identity: the first four residues of thymosin beta-4 are Ser-Asp-Lys-Pro, and prolyl oligopeptidase cleaves them off.
All four refer to the same 487.5 dalton molecule. Only one of them is misleading.
Which Name Is the Misleading One?
Thymosin beta-4 fragment (1-4) is the misleading one, and the reason deserves precision.
Calling something a fragment implies it is a piece of a larger thing you might also buy, and that buying the larger thing gets you the smaller one eventually.
On a catalogue that also sells TB-500, which is itself sold under a name that covers more than one article, that implication is unhelpful.
The tetrapeptide has its own INN, its own 1989 structure determination that predates the thymosin connection, and its own enzymatic fate. It is an endogenous signalling peptide rather than a breakdown product somebody happened to notice.
The relationship runs the other way from what the name suggests. Prolyl oligopeptidase releasing Ac-SDKP from thymosin beta-4 is a described generation route, not evidence that Ac-SDKP is a leftover.
I would order it as goralatide or as Ac-SDKP and let the supplier translate.
There is a practical version of this complaint. Search for thymosin beta-4 fragment and you get results about thymosin beta-4, which is a 43 residue protein with an entirely separate literature.
Search for goralatide or Ac-SDKP and you get the tetrapeptide.
That is not a branding preference. It is the difference between finding the 1989 structure determination and finding work about a molecule ten times the size that happens to contain these four residues at one end.
Anyone doing a literature search on this compound should run it on goralatide and on Ac-SDKP, and use the thymosin name only as a cross-reference rather than as a search term.
What Is Known About Its Enzymatic Fate?
Goralatide is a substrate for angiotensin converting enzyme, and specifically for one of that enzyme’s two active sites.
ACE is unusual in having two catalytically active domains on one polypeptide. The published work by Rousseau and colleagues established that Ac-SDKP is hydrolysed preferentially at the N-terminal site.
That specificity is the reason the peptide appears in the ACE literature at all, and it is a chemical fact about the molecule rather than a claim about anything else.
For laboratory work the consequence is analytical. Any biological matrix containing ACE will consume this peptide, and quantifying it in such a matrix requires either speed or an inhibitor in the collection buffer.
A study measuring Ac-SDKP without controlling for that is measuring how long the sample sat around.
What Does 500 Micrograms Give You in Moles?
About 1.03 micromoles of goralatide per capsule, which is a convenient number and worth knowing.
The molecular weight works out at roughly 487.5 g/mol from the residue masses: serine, aspartate, lysine and proline, minus three waters for the three peptide bonds, plus 42 for the acetyl group.
Divide 500 micrograms by 487.5 and you get 1.026 micromoles. In practice that means one capsule is close enough to one micromole to use as a rough unit.
The container holds 60 of them, so about 61.5 micromoles or 30 milligrams in total.
For a tetrapeptide that is a lot of molecules. Compare it with an acylated peptide ten times the molecular weight, where 30 milligrams would be about 6 micromoles.
What Does the Capsule Format Change?
A goralatide capsule fixes the unit and hides the excipient.
A vial lets you weigh out whatever you want. A capsule commits you to multiples of 500 micrograms, which is fine if your work happens at that scale and awkward if it does not.
The excipient point matters more. A 500 microgram fill in a capsule shell is mostly not peptide. Whatever bulking agent makes the fill weighable and flowable is present in far greater quantity than the active, and the certificate should say what it is.
For a laboratory dissolving capsule contents to make a solution, that excipient goes into the solution too. Its identity and quantity are things you should know before it does.
The 5-amino-1MQ capsule pages in this catalogue take up container life and unit uniformity separately, and both apply here.
There is also the question of what a capsule is for, which on a research listing deserves asking directly. A capsule is a delivery format built to be swallowed.
Supplying a research chemical in one is a packaging decision rather than a use instruction, and this page is not going to pretend the format carries no implication.
For laboratory work the contents come out of the shell and go into solvent, and the shell is waste.
What Should the Certificate Show?
The goralatide sequence written out, with the acetylation on the N-terminal serine stated explicitly.
Observed mass by spectrometry against a calculated 487.5 for the free peptide, and the salt form if it is supplied as one.
Purity by chromatography with the method named.
Content per capsule, measured rather than nominal, and the number of units the measurement covers.
The excipient, named and quantified.
Which name the supplier is working from. A certificate headed thymosin beta-4 fragment and one headed goralatide should describe identical material, and confirming that costs one question.
What Does the Sequence Itself Tell You?
More than four residues usually does, because every residue in goralatide is doing something.
The N-terminal acetyl group is the reason the peptide survives at all. A free alpha-amino group would make it a substrate for aminopeptidases, and acetylation removes that route.
The C-terminal proline is the reason prolyl oligopeptidase is the releasing enzyme. That enzyme cleaves after proline, and here the proline sits at the boundary between the tetrapeptide and the rest of thymosin beta-4.
The aspartate and the lysine give the molecule a charge at neutral pH: one negative, one positive, roughly cancelling. That near-neutrality is why it behaves unremarkably on ion exchange and awkwardly on reverse phase, where four small residues give very little to retain.
Short, acetylated and barely hydrophobic is a difficult combination to chromatograph, which is worth knowing before anybody promises a clean purity trace.
The serine is the only residue with no obvious job beyond being first.
How Should the Container Be Handled?
Sealed, cool, dry and dark, with every opening logged as an exposure event.
Peptides in capsules are protected from light by the shell and from very little else. The container is the barrier.
The sequence has no methionine, no cysteine and no tryptophan, so the reactive residues that dominate handling advice elsewhere in this catalogue are absent.
What it does have is aspartate next to a serine, and aspartyl residues are the slowest-moving hydrolytic liability in peptide chemistry. In a dry sealed container that is a non-issue on any realistic timescale.
In solution it is a different matter, and solutions should be made fresh and used rather than stored.
Do not count on desiccant that came with the container to still be working a year in.
Published Literature
Full citations for the work named above. All four were confirmed against the Crossref publisher record while this page was written. The 1989 paper is the structure determination.
- Lenfant M, Wdzieczak-Bakala J, Guittet E, Prome JC, Sotty D, Frindel E. Proceedings of the National Academy of Sciences. 1989;86(3):779-782. DOI: 10.1073/pnas.86.3.779
- Rousseau A, Michaud A, Chauvet MT, Lenfant M, Corvol P. Journal of Biological Chemistry. 1995;270(8):3656-3661. DOI: 10.1074/jbc.270.8.3656
- Cavasin MA, Rhaleb NE, Yang XP, Carretero OA. Hypertension. 2004;43(5):1140-1145. DOI: 10.1161/01.hyp.0000126172.01673.84
- Robinson S, Lenfant M, Wdzieczak-Bakala J, Riches A. Stem Cells. 1993;11(5):422-427. DOI: 10.1002/stem.5530110509
- 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 goralatide?
The international nonproprietary name for the tetrapeptide N-acetyl-Ser-Asp-Lys-Pro, usually written Ac-SDKP. It weighs about 487.5 g/mol. It is supplied here as 500 microgram capsules for laboratory research use only.
Is goralatide the same as Ac-SDKP?
Yes. Goralatide is the INN, Ac-SDKP is the sequence written in one-letter code with the acetyl group noted, seraspenide appears in the older haematology literature, and thymosin beta-4 fragment (1-4) describes where it is released from. All four are one molecule.
Why is it called a thymosin beta-4 fragment?
Because the first four residues of thymosin beta-4 are Ser-Asp-Lys-Pro and prolyl oligopeptidase releases them as the acetylated tetrapeptide. The name describes a generation route. It postdates the 1989 structure determination, which was done on peptide purified from bone marrow.
Is it a breakdown product of TB-500?
That framing is misleading. The tetrapeptide has its own INN, its own structure determination and its own enzymatic fate, and it was characterised as a distinct signalling peptide before the thymosin connection was made. Ordering it as goralatide or Ac-SDKP avoids the confusion.
What enzyme degrades Ac-SDKP?
Angiotensin converting enzyme. ACE carries two catalytically active domains, and published work by Rousseau and colleagues established that this peptide is hydrolysed preferentially at the N-terminal site.
Why does the ACE relationship matter analytically?
Any biological matrix containing ACE will consume the peptide while the sample sits. Quantifying it in such a matrix needs either fast processing or an inhibitor in the collection buffer, or the measurement records handling time rather than concentration.
How many moles are in one capsule?
About 1.03 micromoles. Five hundred micrograms divided by a molecular weight of roughly 487.5 gives 1.026, so one capsule is close enough to one micromole to use as a rough working unit. Sixty capsules is about 61.5 micromoles, or 30 milligrams.
What is the molecular formula?
C20H33N5O9, about 487.5 g/mol. That is serine, aspartate, lysine and proline joined by three peptide bonds, so three waters are lost from the residue total, with an acetyl group adding 42 at the N-terminus.
What should an Ac-SDKP certificate of analysis show?
The sequence with the N-terminal acetylation stated, observed mass against a calculated 487.5, purity by chromatography with the method named, measured content per capsule rather than nominal, and the excipient named and quantified.
Why does the excipient matter in a capsule?
Because a 500 microgram fill is mostly not peptide. Whatever bulking agent makes it weighable is present in much larger quantity, and it goes into solution alongside the peptide when capsule contents are dissolved.
How should the container be stored?
Sealed, cool, dry and dark. The sequence carries no methionine, cysteine or tryptophan, so the usual oxidation and photodegradation cautions do not apply. The aspartate is a slow hydrolytic site and is not a concern in a dry sealed container.
Is this product for human use?
No. No. These capsules are laboratory research material. They are not a drug, food, cosmetic or dietary product, the FDA has not evaluated them, and they must not be swallowed by a person or given to an animal.
Compliance Statement
Goralatide, also designated Ac-SDKP and thymosin beta-4 fragment (1-4), is supplied exclusively for laboratory research use. It is not a drug, food, cosmetic or dietary product of any kind, and the capsule format does not make it one. 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.
19 reviews for Thymosin Beta-4 Fragment (1-4) (Ac-SDKP) – 500mcg (60 Capsules)