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Thymosin alpha-1 / Studies
Natural fragment · 28 amino acids · 3,108.3 Da

Thymosin alpha-1 studies and research data

PepBank has 615 thymosin alpha-1 studies with results. 332 of them gave thymosin alpha-1, with 1,450 results, grouped by what the studies measured. In each group, results from studies in people come first. Data as of 2026-10-30.

Searches 1,450 results and 1,137 papers. Newer studies from Europe PMC

Results in people
603
42% of 1,450 results
Results in animals
380
26% of 1,450 results
Results in lab cells
462
32% of 1,450 results
From computer models
5
under 1% of 1,450 results
The molecule

Thymosin alpha-1 identity

Identifiers, parent molecule, targets and development stage, from curated data.

Thymosin alpha-1 is the N-acetylated 28-residue N-terminal peptide of human prothymosin alpha (UniProt P06454, residues 2-29). MeSH describes it as a thymus peptide found in thymosin fraction 5 and now made by synthesis (INN thymalfasin). Mouse and cell studies report dendritic-cell activation through Toll-like receptor signalling (TLR9/MyD88); ChEMBL records the mechanism as unknown. Zadaxin (SciClone) was approved for chronic hepatitis B in Singapore, China and the Philippines by 1997; it has US and EU orphan designations but no FDA or EMA approval.

Kind
Natural fragment · 28 residues
Identifiers
UniProtP06454 (opens in a new tab)ChEMBLCHEMBL2103979 (opens in a new tab)PubChem CID16130571 (opens in a new tab)UNIIW0B22ISQ1C (opens in a new tab)DrugBankDB04900 (opens in a new tab)CAS62304-98-7PDB2L9I (opens in a new tab)2MNQ (opens in a new tab)
Parent
Fragment of Prothymosin alpha (human) · residues 2-29UniProt PEPTIDE feature PRO_0000029865 'Thymosin alpha-1' at 2-29; N-acetylserine at position 2 in the N-terminally processed chain.
Development
Approved outside the US and EU (Singapore, China, Philippines)SciClone Pharmaceuticals (Zadaxin)Approved outside the US and EU (see regulatory.other). ChEMBL max_phase 3.0 with phase 3 indication rows for chronic hepatitis C, sepsis, COVID-19 and colorectal carcinoma. In the US and EU it has orphan designations only. Source (opens in a new tab)

Targets

Molecular targets with action and evidence source
TargetActionEvidence
Toll-like receptor 9TLR9Q9NR96 (opens in a new tab)Activation of tlr9/myd88 signalling in plasmacytoid dendritic cells (direct binding not shown in the abstract)primary literature (mouse cytomegalovirus model, 2007); ChEMBL mechanism of action: UnknownSource (opens in a new tab)

Sequence and structure

Residues, differences from the parent, calculated properties and 3D structure. Source values and calculated values are shown separately.

Sequence

28 amino acids · 1 modification

Residues 1 to 10:
SDAAVDTSSE
Residues 11 to 20:
ITTKDLKEKK
Residues 21 to 28:
EVVEEAEN
-OH
  • HydrophobicA V I L M
  • PositiveK R H
  • NegativeD E
  • PolarS T N Q
  • Modified residue

Modifications

N-term (Ser1; UniProt P06454 Ser2)
N-terminal acetyl
N-acetyl-L-serine at residue 1 (GSRS structural modification, UNII W98518XGZ3). UniProt annotates N-acetylserine at its position 2 in the N-terminally processed prothymosin alpha chain.

Alignment to Prothymosin alpha (human)

Calculated from the two sequences. Curated notes are shown as given.

28 of 28 aligned residues identical (100%) · 1 modified residue · Prothymosin alpha (human) 2–29

  • Top row: Prothymosin alpha (human) (parent)
  • Bottom row: Thymosin alpha-1
DAAVDTSS
EITTKDLKEK
KEVVEEAEN
  • Same as parent
  • Substituted
  • Non-canonical or D-form
  • Added
  • Gap
  • Modified side chain or end
  • Parent context

Differences from the parent

  1. 1Parent 2 · analog 1Ser, modified · N-terminal acetylN-acetyl-L-serine at residue 1 (GSRS structural modification, UNII W98518XGZ3). UniProt annotates N-acetylserine at its position 2 in the N-terminally processed prothymosin alpha chain.

Basis: UniProt PEPTIDE feature PRO_0000029865 'Thymosin alpha-1' at 2-29; N-acetylserine at position 2 in the N-terminally processed chain.

Calculated from the two sequences with @pepdb/chem alignToParent (ungapped unless a gap scores higher). The record’s curated notes are shown as given.

Properties

From identity sources

Formula
C129H215N33O55
Molecular weight
3,108.3 g/mol
Monoisotopic mass
3,106.5041 Da

Calculated from the sequence

Average mass
3,108.31 Da
Sum of ExPASy residue masses + water + N-acetyl · ExPASy Compute pI/Mw; FindMod
Monoisotopic mass
3,106.5041 Da
Sum of ExPASy residue masses + water + N-acetyl · ExPASy FindMod
Isoelectric point (pI)
3.81
pH of zero net charge, EMBOSS pKa set · EMBOSS iep, Epk.dat
Net charge at pH 7.4
−6.00
Henderson-Hasselbalch, EMBOSS pKa set · EMBOSS iep, Epk.dat
GRAVY (hydropathy)
−1.029
Mean Kyte-Doolittle hydropathy · Kyte and Doolittle 1982
Negative: hydrophilic on average.
Extinction coefficient, 280 nm (Cys reduced)
0 M⁻¹ cm⁻¹
5500 x Trp + 1490 x Tyr · Pace et al. 1995 (ExPASy ProtParam)
No Trp or Tyr: absorbance at 280 nm cannot measure this peptide.
Instability index
28.15
Dipeptide instability weights (DIWV) · Guruprasad et al. 1990
40 or below: classed as stable (ExPASy).
Aliphatic index
69.6
Mole % A + 2.9 V + 3.9 (I + L) · Ikai 1980
Boman index
3.08 kcal/mol
Mean solubility value (negated) · Boman 2003
Above 2.48: high protein-binding potential (Boman).
Hydrophobic moment (μH)
0.402
Eisenberg scale, 100° per residue, best 11-residue window · Eisenberg et al. 1982, 1984
pI with each pKa set
EMBOSS 3.81Bjellqvist (ExPASy) 4.06IPC peptide 3.87IPC protein 3.93
  • Defined and validated for proteins; use with care for short peptides.
  • Assumes an ideal alpha helix. Many short peptides are not helical.

@pepdb/chem 0.2.0 · EMBOSS pKa set · ExPASy residue masses

Net charge by pH

pI 3.81 · Net charge at pH 7.4: −6.00

Point or use arrow keys

Net charge of Thymosin alpha-1 from pH 0 to 14 (EMBOSS pKa set). Isoelectric point 3.81. Net charge at pH 7.4: -6.00.−10−50+502468101214pHNet chargepH 7.4pI 3.81

Henderson-Hasselbalch, EMBOSS pKa set, N-acetyl. Calculated, not measured.

Show as table
pHNet charge
04.00
13.99
23.89
33.02
4−1.04
5−5.07
6−5.90
7−5.99
8−6.01
9−6.06
10−6.55
11−8.45
12−9.76
13−9.97
14−10.00

Composition

  • Hydrophobic29% (8)
  • Positive14% (4)
  • Negative32% (9)
  • Polar25% (7)

28 residues. Each residue counts in one class; F and W count as aromatic.

A Ala3 · 11%
I Ile1 · 4%
L Leu1 · 4%
M Met0 · 0%
V Val3 · 11%
F Phe0 · 0%
W Trp0 · 0%
Y Tyr0 · 0%
H His0 · 0%
K Lys4 · 14%
R Arg0 · 0%
D Asp3 · 11%
E Glu6 · 21%
N Asn1 · 4%
Q Gln0 · 0%
S Ser3 · 11%
T Thr3 · 11%
C Cys0 · 0%
G Gly0 · 0%
P Pro0 · 0%

3D structure

ExperimentalPDB 2L9I

Loads the 3D viewer (3Dmol.js, about 150 KB) and the model file from RCSB PDB.

RCSB Protein Data Bank · CC0 1.0

2D structure

Thymosin alpha-1 has 28 residues. A full-atom drawing is hard to read at this size; the sequence view is the reference.

SMILES fromPubChem CID 16130571(opens in a new tab)

CC[C@H](C)[C@@H](C(=O)N[C@@H]([C@@H](C)O)C(=O)N[C@@H]([C@@H](C)O)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](C(C)C)C(=O)N[C@@H](C(C)C)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](C)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CC(=O)N)C(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@H]([C@@H](C)O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](C(C)C)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CO)NC(=O)C

Helical wheel

An ideal alpha-helix projection. It shows where the hydrophobic residues fall if the peptide folds as a helix. It does not show that it does.

Helical wheel of Thymosin alpha-1, 28 residues at 100 degrees per residue. Hydrophobic moment 0.28 pointing at 341 degrees.Ser 1, Eisenberg consensus (normalized) -0.18S1Asp 2, Eisenberg consensus (normalized) -0.90D−2Ala 3, Eisenberg consensus (normalized) 0.62A3Ala 4, Eisenberg consensus (normalized) 0.62A4Val 5, Eisenberg consensus (normalized) 1.08V5Asp 6, Eisenberg consensus (normalized) -0.90D−6Thr 7, Eisenberg consensus (normalized) -0.05T7Ser 8, Eisenberg consensus (normalized) -0.18S8Ser 9, Eisenberg consensus (normalized) -0.18S9Glu 10, Eisenberg consensus (normalized) -0.74E−10Ile 11, Eisenberg consensus (normalized) 1.38I11Thr 12, Eisenberg consensus (normalized) -0.05T12Thr 13, Eisenberg consensus (normalized) -0.05T13Lys 14, Eisenberg consensus (normalized) -1.50K+14Asp 15, Eisenberg consensus (normalized) -0.90D−15Leu 16, Eisenberg consensus (normalized) 1.06L16Lys 17, Eisenberg consensus (normalized) -1.50K+17Glu 18, Eisenberg consensus (normalized) -0.74E−18Lys 19, Eisenberg consensus (normalized) -1.50K+19Lys 20, Eisenberg consensus (normalized) -1.50K+20Glu 21, Eisenberg consensus (normalized) -0.74E−21Val 22, Eisenberg consensus (normalized) 1.08V22Val 23, Eisenberg consensus (normalized) 1.08V23Glu 24, Eisenberg consensus (normalized) -0.74E−24Glu 25, Eisenberg consensus (normalized) -0.74E−25Ala 26, Eisenberg consensus (normalized) 0.62A26Glu 27, Eisenberg consensus (normalized) -0.74E−27Asn 28, Eisenberg consensus (normalized) -0.78N28
μH, residues shown
0.284
μH, best 11-residue window
0.402
Arrow direction
341°
Residues
28 · 2 rings of 18
HydrophilicHydrophobic

Eisenberg consensus (normalized) scale · + K, R · − D, E

Assumes an ideal α-helix: 100° per residue, 3.6 residues per turn. The arrow is the mean hydrophobic moment (Eisenberg et al. 1984) and points at the hydrophobic face.

Show as table
PositionResidueAngleEisenberg consensus (normalized)
1S0°-0.18
2D100°-0.90
3A200°0.62
4A300°0.62
5V40°1.08
6D140°-0.90
7T240°-0.05
8S340°-0.18
9S80°-0.18
10E180°-0.74
11I280°1.38
12T20°-0.05
13T120°-0.05
14K220°-1.50
15D320°-0.90
16L60°1.06
17K160°-1.50
18E260°-0.74
19K0°-1.50
20K100°-1.50
21E200°-0.74
22V300°1.08
23V40°1.08
24E140°-0.74
25E240°-0.74
26A340°0.62
27E80°-0.74
28N180°-0.78
Results by area

What the studies measured

People first in each area, then animals, then lab cells. Counts are exact and come from studies that gave the peptide.

Trials and papers
Status and safety
Data