In the field of anticoagulant therapy, a long-standing challenge is how to inhibit thrombosis while minimizing bleeding risk.

Traditional anticoagulants mainly act on key nodes in the coagulation process. Although they can effectively reduce the incidence of thrombotic events, they may also affect normal hemostatic function. Therefore, for many years, researchers have been seeking new coagulation regulatory targets, hoping to achieve a better balance between antithrombotic efficacy and safety.

With the deepening of research on coagulation mechanisms, the serine protease formed by activation of coagulation factor XI — coagulation factor XIa (Factor XIa, FXIa) — has gradually entered researchers' view.

FXIa is located at an important amplification step in the intrinsic coagulation pathway and participates in the continuous amplification of coagulation signals. More and more studies are focusing on FXIa inhibition strategies, hoping to reduce the risk of thrombosis while minimizing the impact on normal hemostasis. Therefore, FXIa has gradually become one of the important research targets for the development of novel anticoagulant drugs.

Whether it is FXIa inhibitor screening, efficacy evaluation, or coagulation mechanism research, there is a fundamental question:

How to accurately measure FXIa activity?

This is precisely why S-2366 is widely used.

FXIa is a serine protease whose activity changes cannot be directly observed by the naked eye. To achieve quantitative detection, researchers usually introduce a chromogenic substrate that can be recognized and cleaved by FXIa.

S-2366 is a classic chromogenic substrate composed of an arginine-p-nitroaniline (Arg-pNA) core structure and an N-terminal pyroglutamyl-prolyl sequence. When FXIa is present in the system, the enzyme recognizes and hydrolyzes a specific peptide bond in the substrate, releasing pNA from the substrate. The released pNA has a characteristic absorption peak at 405 nm, so changes in absorbance can be detected using a microplate reader or spectrophotometer, and FXIa activity can be further calculated.

This detection method features simple operation, intuitive results, and easy quantification. S-2366 has therefore become one of the more classic chromogenic substrates in FXIa activity research.

In addition to FXIa, S-2366 can also be used for activity studies of activated protein C (APC) and plasma kallikrein, giving it certain application value in research on coagulation and the contact activation system.

Chinese Name: Pyroglutamyl-Prolyl-Arginine-p-nitroanilide hydrochloride

English Name: Pyr-Pro-Arg-pNA · HCl

Abbreviation: S-2366

CAS Number: 127428-47-1

Molecular Formula: C22H30N8O6 · HCl

Molecular Weight: 538.98

Specifications: 25 mg/vial (Custom packaging supported)

Form: Off-white crystalline powder

Product Number: G04010014

Signal: Yellow (405 nm)

S-2366 is a pNA chromogenic substrate with a mature application foundation in coagulation-related enzyme activity research. GeneSeqTools Bioscience & Technology can provide S-2366 in multiple product forms, including the hydrochloride salt, free base, and MNA derivative, to meet different detection systems and procurement needs.

1. CAS:2070009-26-4, pGlu-Pro-Arg-MNA monoacetate

2. CAS:130835-45-9, pGlu-Pro-Arg-MNA

3. CAS:127428-47-1, S-2366 (Pyr-Pro-Arg-pNA·HCl)

4. CAS:72194-57-1, S-2366 (Pyr-Pro-Arg-pNA free base)

1. Coagulation factor XIa (FXIa) activity detection

Used for detection and quantification of FXIa amidolytic activity in purified enzyme systems and in complex sample systems established through methodology.

Mainly applied to:

• FXIa activity assay

• FXI-related research

• Coagulation mechanism research

• Methodology development

2. Coagulation factor XIa (FXIa) inhibitor screening and efficacy evaluation

Used for in vitro enzymatic screening, inhibitory activity evaluation, and related kinetic studies in FXIa inhibitor development.

Mainly applied to:

• FXIa inhibitor screening

• Anticoagulant drug development

• CRO efficacy evaluation platforms

• Enzyme kinetics research

3. Activated protein C (APC) and contact activation-related enzymology research

Used for activated protein C activity detection and contact activation system-related enzymology research.

Mainly applied to:

• Protein C pathway research

• Activated protein C activity evaluation

• Contact activation system research

• Basic hematology research

✅ HPLC purity chromatogram verification, traceable quality

Each batch of S-2366 is verified for purity by HPLC purity chromatogram. Customers can verify batch by batch, meeting the chromatogram-level data requirements for raw material incoming inspection by reagent companies.

✅ Mature methodology foundation, reducing system development risk

Compared with novel substrates, S-2366 has accumulated a large number of public literature and experimental experience in the coagulation research field. R&D personnel can directly refer to existing protocols to establish detection systems, reducing method development cycles.

✅ Optimized substrate selectivity, clearer signal attribution

S-2366 uses the Pyr-Pro-Arg-pNA structure and has a clear FXIa-related enzymology application foundation. In FXIa activity detection systems, pNA can be released by substrate hydrolysis and quantified by absorbance change at 405 nm, facilitating researchers in establishing and optimizing corresponding detection methods.

✅ Domestic supply, controllable lead time and cost

GeneSeqTools Bioscience & Technology provides in-stock domestically produced S-2366 using an independently developed synthesis process, helping reagent companies shorten stocking cycles, reduce raw material costs, and reduce dependence on imported supply chains.

✅ Synergistic coagulation substrate product matrix, one-stop procurement

S-2366, together with GeneSeqTools Bioscience & Technology's existing thrombin substrates, FXa substrates, etc., forms a coagulation detection substrate product matrix. Customers can complete the procurement of multiple coagulation substrates from the same supplier, reducing supplier management costs.

Q1: What is S-2366 mainly used to detect?

A: The most classic application of S-2366 is coagulation factor XIa (FXIa) activity detection. It can also be used for research related to activated protein C and plasma kallikrein.

Q2: How is purity verified? Is there a report?

A: S-2366 is tested for purity by HPLC, and batch quality is verified through HPLC purity chromatograms. According to procurement and quality control needs, corresponding batch quality testing data can be provided to facilitate customer raw material acceptance and batch traceability.

Q3: What is the difference between S-2366 and general thrombin substrates?

A: Although both belong to pNA chromogenic substrates, their substrate peptide sequences and main application directions differ. S-2366 uses the Pyr-Pro-Arg-pNA structure and has a clear application foundation in FXIa, APC, and other coagulation-related protease activity research; while thrombin-related detection usually selects substrate systems designed for thrombin substrate recognition characteristics.

Therefore, substrate selection should be determined based on the target enzyme and specific detection system. For FXIa activity detection or FXIa inhibitor research, S-2366 is a substrate choice with a mature application foundation.

Q4: What is the difference between S-2366 and S-2288?

A: Both S-2366 and S-2288 are pNA chromogenic substrates, but their main application directions differ. S-2366 has a relatively mature application foundation in FXIa and APC-related activity detection; S-2288 is commonly used for activity research related to serine proteases such as t-PA.

Therefore, if the core project goal is FXIa activity analysis or FXIa inhibitor screening, S-2366 has a higher degree of application match with the target enzyme; if the research object involves other proteases such as t-PA, the corresponding substrate should be selected based on the specific detection target.

Q5: What method is usually used for FXIa activity detection?

A: In FXIa activity research, a common detection approach is to obtain FXIa using an FXI activation system, then add S-2366 for enzymatic reaction, and evaluate FXIa activity by monitoring absorbance changes at 405 nm. Specific experimental conditions need to be optimized based on factors such as enzyme source, sample type, buffer system, substrate concentration, and detection equipment. Because S-2366 has a mature FXIa-related application foundation, it can be used as a substrate choice for establishing such chromogenic detection systems.

Q6: How should S-2366 products be stored and used?

A: S-2366 is a lyophilized powder and should be stored sealed, protected from light, and at low temperature. When using, select an appropriate reconstitution solution and working concentration based on the specific detection system, and try to avoid repeated freeze-thaw cycles. For kit development and large-scale applications, it is recommended to validate reconstitution conditions, stability, and working solution storage time based on the actual system.