Tetracosactide Acetate | CAS 16960-16-0 / 60189-34-6 | ACTH(1-24) Analogue (Research Use Only) | Knowlux

Product Description

Tetracosactide Acetate, CAS 16960-16-0 (net peptide) / 60189-34-6 (acetate salt), is a synthetic 24-amino-acid peptide corresponding to the N-terminal fragment of human adrenocorticotropic hormone (ACTH), supplied by Knowlux for laboratory research use. The sequence is H-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-Gly-Lys-Lys-Arg-Arg-Pro-Val-Lys-Val-Tyr-Pro-OH, with a free N-terminus and a free C-terminal proline carboxylate. The net peptide molecular formula is C136H210N40O31S and the molecular weight is 2933.44 g/mol. Each lot is released with a lot-specific COA, MSDS and analytical traceability.

CAS and Salt Form Clarification: The CAS assignment for Tetracosactide is one of the most inconsistently applied in peptide procurement, and the distinction between registries directly affects the reported molecular formula and molecular weight. CAS 16960-16-0 is the net peptide registry, corresponding to formula C136H210N40O31S with a molecular weight of 2933.44 to 2933.48 g/mol. CAS 60189-34-6 is the acetate salt registry. However, suppliers differ in the acetate stoichiometry they assign to this second CAS: some list C138H214N40O33S with MW 2993.5 (consistent with a monoacetate or a defined acetate adduct), while the Japanese Accepted Names database records the hexaacetate as C136H210N40O31S.6C2H4O2 with MW 3293.80. A third pattern appears on some Chinese supplier pages, which apply CAS 16960-16-0 to the product name "Tetracosactide Acetate" while reporting the net peptide formula C136H210N40O31S and MW 2933.44. Knowlux specifies the salt stoichiometry, acetate content, and water content per lot on the COA. Buyers should confirm the counter-ion basis and the associated molecular weight before procurement, as the difference between net peptide (2933.44) and hexaacetate (3293.80) is approximately 360 g/mol.

Sequence Verification Note: The 24-residue sequence Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-Gly-Lys-Lys-Arg-Arg-Pro-Val-Lys-Val-Tyr-Pro is confirmed by ChEBI, Bachem, MedChemExpress, and GLPBIO. The peptide contains a methionine residue at position 4, introducing a thioether side chain susceptible to oxidation to methionine sulfoxide. The tryptophan at position 9 is also oxidation-sensitive. Unlike the disulfide-constrained peptides in the Ziconotide and Carbetocin families, Tetracosactide is linear and contains no cysteine residues.

Product Parameters

Item	Specification
Product Name	Tetracosactide Acetate
Synonyms	Cosyntropin; Tetracosactrin; ACTH (1-24); alpha1-24-Corticotropin; Synacthen
CAS No.	16960-16-0 (net peptide); 60189-34-6 (acetate salt)
Molecular Formula	C136H210N40O31S (net peptide); acetate formula varies by stoichiometry
Molecular Weight	2933.44 g/mol (net peptide); acetate salt MW depends on counter-ion load
Sequence (1-letter)	SYSMEHFRWGKPVGKKRRPVKVYP
Sequence Length	24 amino acids, linear
Key Structural Features	Free N-terminus; free C-terminal Pro-OH; Met4 thioether; Trp9 indole; no cysteine or disulfide bonds
Appearance	White to off-white powder
Solubility	H2O >=50 mg/mL (17.04 mM; sonication and warming recommended)
Purity	>=97.0% to >=98.0% (HPLC); >=99.0% available (supplier-dependent)
Identity	Confirmed by LC-MS
Grade	Research grade
Counter-ion	Acetate (lot-specific, declared on COA)
Acetate Content	<=12.0% (supplier specification)
Peptide Content	>=80.0% (supplier specification); >=60.0% minimum in some batch COAs
Water Content	<=8.0% (supplier specification)
Single Impurity	<=2.0% (HPLC; <=1.0% available)
Amino Acid Composition	+/-10% of theoretical (supplier specification)
Bacterial Endotoxins	<=50 EU/mg (supplier specification); <=1.0 EU/mg available
Storage	See Storage and Stability section
Packaging	1 mg / 5 mg / 10 mg / 50 mg / 100 mg vial; bulk on request
Application	Laboratory research use only
Origin	China

Product Details

1. Overview

Tetracosactide (cosyntropin) is a synthetic peptide comprising the first 24 amino acids of human ACTH. This 24-residue segment retains the full biological activity of the parent hormone at the melanocortin-2 receptor (MC2R) while being substantially shorter and less immunogenic than the full 39-residue ACTH sequence. The peptide stimulates the adrenal cortex to produce and release corticosteroids, principally cortisol, along with mineralocorticoids and, to a lesser extent, androgens. In clinical medicine, Tetracosactide Acetate is used as a diagnostic agent for adrenocortical insufficiency (the short Synacthen test) and, in some jurisdictions, for therapeutic indications in rheumatology, dermatology, and neurology. The material supplied under this specification is research-grade and is not intended for human administration. Knowlux supplies this compound strictly for laboratory investigation of melanocortin receptor pharmacology, adrenal steroidogenesis, and HPA-axis biology.

2. Receptor Pharmacology and Selectivity

Tetracosactide is a potent agonist primarily at MC2R, the melanocortin receptor subtype expressed on adrenocortical cells that mediates ACTH-stimulated cortisol synthesis. MC2R is unusual among melanocortin receptors in that it requires the accessory protein MRAP for functional cell-surface expression and ligand binding. Downstream signaling proceeds through Gs-mediated adenylyl cyclase activation, elevated intracellular cAMP, and protein kinase A-dependent transcription of steroidogenic enzymes. Beyond MC2R, Tetracosactide exhibits agonist activity across the other melanocortin receptor subtypes. BenchChem's comparative pharmacology compilation characterizes Tetracosactide as an agonist at hMC1R, a potent agonist at hMC2R, and an agonist at hMC3R and hMC4R, with the note that its hMC4R affinity is 5- to 34-fold lower than that of rat MC4R. MedChemExpress separately reports an EC50 of 0.65 nM for human MC4R activation by Tetracosactide acetate, indicating that under some assay conditions the peptide retains nanomolar potency at this subtype. These values are assay- and system-dependent and are provided for scientific reference only. The multi-receptor activity profile is a relevant consideration for any research design in which MC2R-selective stimulation is the intended outcome; control experiments with MC2R-null or MRAP-deficient systems may be warranted where off-target melanocortin engagement could confound interpretation.

3. Research Applications

Published pharmacological characterizations and documented protocols describe the following research applications:

• MC2R/MRAP-dependent adrenal steroidogenesis and cortisol release assays

• Adrenocortical insufficiency and HPA-axis function research models

• Comparative melanocortin receptor pharmacology across MC1R, MC2R, MC3R, MC4R, and MC5R

• ACTH fragment structure-activity studies (the 1-24 segment as a fully active minimal sequence)

• Peptide immunogenicity and fragment-length comparisons relative to ACTH(1-39)

• Reference standard development for HPLC and LC-MS analytical methods

These descriptions are derived from published research and are provided for scientific reference only. They do not constitute clinical guidance or dosing recommendations.

Quality Control

Test Item	Method	Acceptance Criteria
Purity	RP-HPLC	>=98.0% (Chinese supplier standard); >=97.0% (research grade)
Identity & Molecular Mass	LC-MS (deconvoluted)	Consistent with structure (2933.44 +/- 1 for net peptide)
Single Impurity	RP-HPLC	<=2.0% (<=1.0% available)
Acetate Content	HPLC or ion chromatography	<=12.0% (standard); <=10.0% (higher grade)
Water Content	Karl Fischer	<=8.0%
Peptide Content	Amino Acid Analysis or Nitrogen	>=80.0% (standard); >=85.0% (higher grade); >=60.0% minimum in some batch COAs
Amino Acid Composition	AAA	+/-10% of theoretical
Bacterial Endotoxins	LAL or chromogenic	<=50 EU/mg (standard); <=1.0 EU/mg available
Appearance	Visual	White to off-white powder

The quality specifications for Tetracosactide Acetate vary across supplier tiers, and the variation is larger than for most peptides in this catalogue. Chinese supplier standards specify HPLC purity >=98.0%, acetate content <=12.0%, water content <=8.0%, peptide content >=80.0%, endotoxin <=50 EU/mg, and amino acid composition within +/-10% of theoretical. A MedChemExpress batch COA reports HPLC purity of 99.35% and peptide content of 79.85%, which is marginally below the 80.0% supplier-standard threshold but consistent with the lot-specific acceptance range. BenchChem lists a peptide content specification of >=85.0% and an acetate limit of <=10.0%, reflecting a higher-grade tier. Carl Roth specifies >=97% HPLC purity for its research-grade catalogue item. The British Pharmacopoeia and European Pharmacopoeia monographs for Tetracosactide specify a content assay of 90.0% to 102.0% calculated on the anhydrous, acetic acid-free substance, and by convention assign 1 microgram of Tetracosactide an activity of 1 International Unit (IU). This assay convention is useful as an orthogonal check against HPLC area-percent purity: a lot that meets the 98% HPLC threshold may still fall outside the 90.0%-102.0% content window if the peptide content on an anhydrous, acetate-free basis is low. Researchers preparing molar solutions should use the peptide content value rather than the HPLC purity figure. Full COA, MSDS, and lot-specific chromatograms are issued with each shipment.

Solubility and Handling

Solubility: Tetracosactide Acetate is freely soluble in water. MedChemExpress reports H2O solubility of 100 mg/mL (34.09 mM) with ultrasonic assistance. GLPBIO specifies water solubility of >=50 mg/mL (17.04 mM) and recommends warming the tube to 37C and shaking in an ultrasonic bath to achieve higher concentrations. HQ Tech lists solubility in water and dilute acids, with insolubility in organic solvents. TargetMol reports PBS (pH 7.2) solubility of 10 mg/mL. The high aqueous solubility is consistent with the peptide's hydrophilic, highly charged character (multiple Lys and Arg residues) and distinguishes its handling profile from the DMSO-favoring, hydrophobic peptides such as Abarelix and Pentagastrin. For stock preparation, water or PBS is the preferred solvent; DMSO is not required and may offer no solubility advantage for this peptide. Prepare solutions fresh and aliquot to avoid repeated freeze-thaw cycles.

Handling Precautions: Use powder-handling containment (glove box or fume hood with particulate control). Avoid inhalation of fine powder. Wear nitrile gloves, lab coat, and eye protection. The Met4 and Trp9 residues are susceptible to oxidation; protect from prolonged exposure to air, light, and oxidizing agents. HQ Tech specifies storage protected from light and moisture. Follow institutional chemical hygiene plans for research peptides.

Storage and Stability

Format	Temperature	Shelf Life
Lyophilized Powder	-20C, sealed, desiccated, protected from light	3 years (TargetMol, GLPBIO)
Lyophilized Powder	-80C, sealed, desiccated	2 years (MedChemExpress)
Lyophilized Powder	-20C, sealed, desiccated	1 year (MedChemExpress); -20 +/- 5C long-term (Bachem)
Reconstituted Solution	-80C, aliquoted	1 year (TargetMol)
Reconstituted Solution	Below -20C, aliquoted	Several months (GLPBIO)

Storage guidance converges on -20C as the standard long-term condition for the lyophilized powder, with desiccation and light protection. Bachem specifies -20 +/- 5C for long-term storage of the API. TargetMol and GLPBIO list 3 years at -20C for powder, with TargetMol additionally specifying 1 year at -80C for solutions and shipping with blue ice. MedChemExpress offers a more conservative tier of 2 years at -80C and 1 year at -20C for powder, with solutions stable for 6 months at -80C or 1 month at -20C. GLPBIO notes that stock solutions can be stored below -20C for several months. For long-term archival storage, -80C is the conservative choice; -20C is adequate for routine working inventories within the supplier-specified window. The lyophilized powder is hygroscopic; equilibrate vials to room temperature before opening to prevent condensation. Protect from light and moisture throughout storage.

Documentation Support

Per lot: COA, MSDS, certificate of origin, HPLC chromatogram, and mass spectrometry data. Acetate content, water content, peptide content, amino acid composition, and endotoxin data available on request. Custom specifications and third-party inspection can be arranged on a project basis.

About Knowlux

Knowlux Biotechnology is a GMP-oriented manufacturer and supplier of peptides, APIs and fine-chemical research compounds, operating from Hubei, China. We serve research groups, CDMOs and distributors in more than 40 countries, and support contract synthesis, custom packaging and technical documentation requests.

Compliance Statement

FOR RESEARCH USE ONLY. NOT FOR HUMAN USE. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE.

This product is supplied for laboratory research use only. It is not for human or animal administration, not for diagnostic or therapeutic use, not for retail sale, and not for personal use. Tetracosactide is an approved diagnostic and therapeutic agent in certain jurisdictions (including the Synacthen short test for adrenocortical insufficiency); however, the material offered under this specification is research-grade and is not intended for clinical use. The purchaser is responsible for verifying product specifications against their specific research requirements and for compliance with all applicable institutional, local, and national regulations governing research chemical acquisition, storage, and use. Research context statements are for scientific reference only and do not constitute medical advice, promotional claims, or dosing guidance.

Data Verification Notes: The net peptide molecular formula C136H210N40O31S and molecular weight 2933.44-2933.48 are confirmed by Bachem, MedChemExpress, ChEBI, and the Czech Pharmacopoeia. The sequence SYSMEHFRWGKPVGKKRRPVKVYP is confirmed by ChEBI, Bachem, MedChemExpress, and GLPBIO. The CAS mapping (16960-16-0 = net peptide; 60189-34-6 = acetate salt) is confirmed by Bachem. The acetate formula discrepancy is explicitly addressed: InvivoChem and TargetMol list C138H214N40O33S (MW ~2993.5) for CAS 60189-34-6, while the JAN database records the hexaacetate C136H210N40O31S.6C2H4O2 (MW 3293.80). Both assignments are retained in the CAS Clarification section rather than reconciled into a single figure, because the supplier-dependent acetate stoichiometry is a genuine source of variability rather than a data error. The MC4R EC50 of 0.65 nM is from MedChemExpress; the qualitative MC2R/MC1R/MC3R/MC4R agonist classification is from BenchChem. The BP/Ph.Eur. content assay (90.0%-102.0% on anhydrous, acetic acid-free basis) and the 1 microgram = 1 IU convention are from the British Pharmacopoeia monograph.

Formatting Note: All formulas, sequences, and comparison operators use plain ASCII notation to prevent character corruption on the platform. The micro symbol has been rendered as "microgram" or "ug" to avoid non-ASCII character risk. Section headings, table alignment, and spacing follow the approved product detail pattern. No trailing spaces or non-breaking characters are used; tables use consistent pipe alignment.