Ac-FAAGRK-pNA is a chromogenic peptide substrate for dengue virus NS2B-NS3 protease. The hexapeptide sequence Ac-Phe-Ala-Ala-Gly-Arg-Lys represents the P6–P1 residues associated with the dengue NS3/NS4A polyprotein cleavage site and is coupled to p-nitroaniline (pNA) for absorbance-based protease assays.
This defined substrate can be used to investigate viral protease activity, substrate recognition, enzyme kinetics and inhibition of the NS2B-NS3 protease complex.
Product Information
| Property | Specification |
|---|---|
| Product Name | Ac-FAAGRK-pNA |
| Catalog No. | AS2526 |
| Sequence | Ac-Phe-Ala-Ala-Gly-Arg-Lys-pNA |
| Sequence Shortening | Ac-FAAGRK-pNA |
| Peptide Length | 6 amino-acid residues |
| Molecular Formula | C37H54N12O9 |
| Molecular Weight | Approximately 810.93 Da |
| Reporter Group | p-Nitroaniline (pNA) |
| Research Enzyme | Dengue virus NS2B-NS3 protease |
| Cleavage-Site Context | NS3/NS4A |
NS3/NS4A Cleavage-Site Recognition
Dengue NS2B-NS3 protease recognizes basic residues near the scissile bond at several viral polyprotein junctions. The FAAGRK sequence contains Arg-Lys at the P2–P1 positions, consistent with the preference of the viral protease for basic residues near the cleavage site.
The upstream P6–P3 residues provide additional sequence context and influence how the substrate interacts with the protease-binding pockets.
In a foundational study using recombinant dengue virus type 2 NS2B-NS3 protease, Ac-FAAGRK-pNA was processed with a reported Km of approximately 78 µM and a catalytic efficiency of approximately 219 M−1s−1 under the study conditions.
We recommend treating these kinetic values as reference data rather than universal assay specifications because enzyme construct, buffer composition, ionic strength, pH and temperature can substantially affect measured activity.
Chromogenic Protease Assays
Proteolytic cleavage releases free p-nitroaniline, generating an absorbance signal that can be monitored spectrophotometrically, commonly near 405 nm.
This format is suitable for purified-enzyme kinetics, inhibitor evaluation and assay-development workflows where a direct colorimetric readout is preferred.
Experimental and Quality Considerations
NS2B is an essential cofactor for the catalytically active dengue NS3 protease complex. Differences in recombinant protease design can therefore affect apparent substrate turnover and should be documented when results are compared between laboratories.
For quantitative enzymology, we recommend confirming peptide identity, reporter conjugation and chromatographic purity. Our Peptide Quality Control capabilities support analytical HPLC and mass spectrometry according to the selected specification.
Frequently Asked Questions
What does pNA do in Ac-FAAGRK-pNA?
pNA is the chromogenic leaving group. Protease-mediated cleavage releases p-nitroaniline, allowing activity to be monitored by absorbance.
Does this peptide represent a dengue polyprotein cleavage site?
Yes. The FAAGRK sequence represents the P6–P1 portion associated with the NS3/NS4A cleavage-site region used in dengue protease substrate studies.
Can modified dengue protease substrates be synthesized?
Sequence variants, alternative reporters and inhibitor-oriented peptide designs can be evaluated through Chemical Peptide Synthesis.