Compound monograph
Ac-SDKP (Goralatide)
Ac-SDKP is the acetylated N-terminal tetrapeptide of thymosin beta-4, generated from the parent by sequential enzymatic processing.
01
Identity & nomenclature
Ac-SDKP is the acetylated N-terminal tetrapeptide of thymosin beta-4, generated from the parent by sequential enzymatic processing.
Ac-SDKP is not thymosin beta-4 and not a generic TB-500 fragment. It is one specifically processed N-terminal tetrapeptide and is not a stand-in for the parent's other sequence regions. Release and degradation are also different processes: meprin-alpha and prolyl oligopeptidase participate in generating it, while angiotensin-converting enzyme hydrolyses it. ACE must not be recorded as the releasing mechanism.
Canonical name: Goralatide.
Declared aliases and development codes: Ac-SDKP, Seraspenide, N-acetyl-seryl-aspartyl-lysyl-proline.
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Molecular properties
| Molecular formula | C20H33N5O9 |
|---|---|
| Molecular mass | 487.51 Da |
| CAS Registry Number | 120081-14-3 |
| PubChem CID | 65938 |
| UNII | H041538E9P |
| One-letter sequence | SDKP |
| Three-letter sequence | Ser–Asp–Lys–Pro |
| Terminal groups | N-terminal acetylation; Free C-terminal carboxyl |
Four residues, all L, N-terminally acetylated with a free C-terminal carboxyl. The acetyl sits on the serine alpha-amino group. An acetyl on the lysine side chain instead would preserve the elemental composition while describing a different molecule.
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Structural characteristics
The release pathway is the best-characterised thing about this compound, and it is sequential rather than direct. In a purified system neither meprin-alpha nor prolyl oligopeptidase alone released Ac-SDKP from intact thymosin beta-4; only both together did, supported by inhibitor experiments and by kidneys from meprin-alpha knockout animals failing to release it. Earlier work had identified prolyl oligopeptidase as responsible, and the later finding refines that rather than overturning it. Separate work comparing parent, fragment, and cleavage inhibition supports a conditional statement — that some thymosin beta-4-associated effects depend on Ac-SDKP being generated — and does not support the converse, that activity measured with isolated Ac-SDKP can be attributed to the intact parent. No direct cognate receptor is established.
Terminal features: N-terminal acetylation, Free C-terminal carboxyl.
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Molecular targets & mechanisms
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Analytical considerations
Confirmation needs N-terminal rather than lysine-side-chain acetylation established by an orthogonal method, since the two are identical by mass. Ordinary aspartate versus isoaspartate connectivity also survives an intact-mass match. A terminal acid and an amide differ in exact mass and should be distinguished explicitly. When studying formation from the parent, measure both the intact parent and the released tetrapeptide; a downstream cellular response is not evidence that cleavage occurred.
Disagreements and mix-ups
Points where sources disagree about this compound's identity, or where a name or form is easily confused with another, as noted in this record. The discrepancy register quotes the passage for each one.
Often mixed up · Name or substance
Ac-SDKP vs thymosin beta-4 and TB-500
What the studies reported
Each finding describes one cited study in its stated model. These observations are specific to that study and do not establish effects in other settings.
Cell and tissue studies
Thymosin beta-4 with meprin-alpha and prolyl oligopeptidase
Kumar et al. observed Ac-SDKP release when thymosin beta-4 was incubated with both meprin-alpha and prolyl oligopeptidase in a cell-free enzyme assay.
Reference [1]Thymosin beta-4 with individual peptidases
Kumar et al. observed no Ac-SDKP release when thymosin beta-4 was incubated with either meprin-alpha or prolyl oligopeptidase alone in a cell-free enzyme assay.
Reference [1]Rat kidney homogenates
Kumar et al. found that actinonin blocked Ac-SDKP release from thymosin beta-4 in rat kidney homogenates.
Reference [1]Kidney cortex homogenates
Cavasin et al. observed time-dependent Ac-SDKP generation from thymosin beta-4 in kidney cortex homogenates and significant inhibition of this generation by prolyl oligopeptidase inhibitors.
Reference [2]
Animal studies
Wild-type and PAI-1 knockout mice with unilateral ureteral obstruction
Zuo et al. observed significantly decreased collagen and fibronectin deposition with Ac-SDKP in wild-type and PAI-1 knockout mice with renal fibrosis following unilateral ureteral obstruction.
Reference [3]
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Verified bibliography
Cited studies by type
The 3 papers this record cites, counted by the kind of work each reports. A count is the size of this record's selection, not of the research that exists, and says nothing about results, safety, effectiveness or approval.
A paper can report more than one kind of work. Each count opens those papers in the bibliography. Compare every record on the Evidence Map.
Reference 1
The anti-inflammatory peptide Ac-SDKP is released from thymosin-β4 by renal meprin-α and prolyl oligopeptidase.Kumar N, Nakagawa P, Janic B, Romero CA, Worou ME, Monu SR, Peterson EL, Shaw J, Valeriote F, Ongeri EM, Niyitegeka JM, Rhaleb NE, Carretero OA
American journal of physiology. Renal physiology · 2016-03-09 · Journal Article
currentReference 2
Prolyl oligopeptidase is involved in release of the antifibrotic peptide Ac-SDKP.Cavasin MA, Rhaleb NE, Yang XP, Carretero OA
Hypertension (Dallas, Tex. : 1979) · 2004-03-22 · Journal Article
currentReference 3
Thymosin β4 and its degradation product, Ac-SDKP, are novel reparative factors in renal fibrosis.Zuo Y, Chun B, Potthoff SA, Kazi N, Brolin TJ, Orhan D, Yang HC, Ma LJ, Kon V, Myöhänen T, Rhaleb NE, Carretero OA, Fogo AB
Kidney international · 2013-06-05 · Journal Article
current
Study models of these references
What kind of experiment each cited paper reports, taken from its abstract unless marked. Not a summary of results.
| Reference | Study models |
|---|---|
| Kumar N et al. 2016 | Study models reported: in vitro; animal (rat) · from the abstract |
| Cavasin MA et al. 2004 | Study models reported: in vitro; animal (rat) · from the abstract |
| Zuo Y et al. 2013 | Study models reported: animal (mouse) · from the abstract |
Record history
Published 2026-09-13.
- : Sequence and structure
Each entry names the parts of this record that changed on that date. Changes to links between records and to catalogue links are not listed. This history covers the tracked record fields; study findings are not listed here.
Cite this record: Purely Peptides Research Library. Ac-SDKP (Goralatide). Published 2026-09-13; updated 2026-10-15. https://purelypeptides.org/research/compounds/ac-sdkp/
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Methodology & citation verification
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