Ac-VDQQD-pNA is a pentapeptide chromogenic substrate used in caspase-2 research. It combines the Val-Asp-Gln-Gln-Asp recognition sequence with a C-terminal p-nitroaniline reporter.

The longer VDQQD motif provides a different recognition profile from the shorter DEVD- and YVAD-family substrates used for other caspases.

Product Information

Caspase-2 Substrate Recognition

Caspase-2 has substrate-recognition characteristics that differ from the classical DEVD preference of executioner caspases. VDQQD is one peptide motif used to investigate this enzyme experimentally.

Published kinetic comparisons have shown measurable caspase-2 cleavage of Ac-VDQQD-pNA with substantially weaker processing by some other tested family members.

Sequence preference is still assay-dependent, so the peptide should not be treated as a universal proof of caspase-2 activity in complex samples.

Chromogenic Readout

Cleavage releases pNA, generating an absorbance signal that can be followed around 405 nm. This format supports purified-enzyme measurements and assay development without requiring a fluorescence detector.

Experimental Controls

For cell or tissue lysates, we recommend pairing the substrate with inhibitor controls or orthogonal measurements because multiple proteases may contribute to total peptide cleavage.

Researchers requiring project-specific substrate sequences can use our Chemical Peptide Synthesis capabilities.

Frequently Asked Questions

How many residues are in the VDQQD recognition sequence?

VDQQD contains five amino-acid residues.

What signal does this substrate generate?

Proteolytic cleavage releases p-nitroaniline, producing a measurable colorimetric signal.

Can Ac-VDQQD-pNA alone prove that caspase-2 is active?

Not in every biological sample. Appropriate controls are recommended because protease substrate preferences can overlap.

Research Use Only.