Assays for Plasma ADAMTS13 Activity and Inhibitors Using Recombinant FRETS-VWF73 Peptide.
FRETS-VWF73 isn’t just another synthetic peptide. It’s the engine behind a breakthrough assay for measuring ADAMTS13 activity — a key step in understanding and diagnosing thrombotic thrombocytopenic purpura (TTP). This rare but serious condition happens when ADAMTS13, an enzyme that cleaves von Willebrand factor, is missing or blocked. Without it, ultra-large VWF multimers trigger dangerous clots.
Methods Mol Biol
by Gralnek SH, Liu S, Zheng XL
“Assays for Plasma ADAMTS13 Activity and Inhibitors Using Recombinant FRETS-VWF73 Peptide. Gralnek SH(1), Liu S(1), Zheng XL(2). Author information: (1)Department of Pathology and Laboratory Medicine, The University of Kansas Medical Center, Kansas City, KS, USA. (2)Department of Pathology and Laboratory Medicine, The University of Kansas Medical Center, Kansas City, KS, USA. xzheng2@kumc.edu. Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy caused by severe deficiency of plasma ADAMTS13 activity. ADAMTS13 cleaves ultra-large von Willebrand factor (ULVWF) multimers, thus preventing the pathological accumulation of platelet-VWF aggregates at sites of vascular injury. The deficiency of ADAMTS13 can be congenital or more commonly immune-mediated, involving the formation of autoantibodies that bind and inactivate plasma ADAMTS13 activity. A simple, rapid, and cost-effective assay is crucial for the diagnosis of TTP and for the conduction of translational research relevant to ADAMTS13 function. Here, we describe a FRETS-rVWF73 assay for ADAMTS13 activity and inhibition, starting from the peptide substrate expression, purification, labeling, detailed assay protocol, and potential pitfalls. This assay can be used to quantify ADAMTS13 enzymatic activity and inhibition in various biological conditions for translational research. © 2026. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.”
Researchers at the University of Kansas Medical Center have detailed a straightforward, cost-effective method for running these assays using recombinant FRETS-VWF73. The peptide acts as a precise substrate, lighting up (literally, via fluorescence) when cleaved by ADAMTS13. That means clear, direct measurement of enzyme activity and, just as important, the detection of inhibitors — like the autoantibodies common in acquired TTP.
Key takeaway: The FRETS-VWF73 assay is fast, scalable, and adaptable to many research settings. It’s not just for clinical diagnostics; it’s a powerful tool for basic and translational research into the complex world of ADAMTS13 and VWF interactions.
Researchers get:
Step-by-step peptide expression and purification protocols
Guidance on labeling and running the fluorescence assay
Tips for troubleshooting and avoiding common pitfalls
This kind of peptide-driven assay is a perfect example of how targeted peptide research makes high-impact translational work possible. If you want to see how other synthetic peptides are pushing research boundaries, explore the peptide research index for more examples.
Bottom line: Peptide substrates like FRETS-VWF73 are turning what used to be complex, expensive testing into practical, everyday tools for the lab. Expect more peptide-based innovation in enzyme activity assays soon.
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