HPRT Assay Kit

PRECICE® HPRT Assay Kit
Spectrophotometric, microplate format

Including active human HPRT enzyme

Developed by our R&D team in 2011, the PRECICE® HPRT Assay Kit was the first non-radioactive solution for measuring HPRT activity, designed for user-friendly application in a 96-well plate format. ResarchGate

HPRT (EC 2.4.2.8) is a pivotal enzyme in the purine salvage pathway, encoded by the highly polymorphic HPRT1 gene. Over 300 pathogenic variants have been documented, with mutations linked to partial or complete enzymatic deficiency. Complete HPRT deficiency results in Lesch-Nyhan syndrome, a rare X-linked genetic disorder. In other cases, HPRT deficiency may contribute to secondary forms of gout—one of the most prevalent purine metabolism disorders (Ceballos-Picot I. et al., 2010). Due to the extensive variability of the HPRT1 gene, genetic diagnosis can be challenging. Traditional functional assays rely on red blood cell lysates and chromatographic detection with radiolabeled ¹⁴C-hypoxanthine (Cartier P. et al., 1968).

Assay Principle:
HPRT activity is determined by measuring the enzymatic conversion of hypoxanthine to inosine monophosphate (IMP). IMP is then oxidized to xanthosine monophosphate (XMP) by recombinant IMP dehydrogenase (IMPDH), reducing NAD⁺ to NADH in the process. The accumulation of NADH is continuously monitored by absorbance at 340 nm, enabling real-time kinetic analysis of HPRT activity.

HPRT enzyme Molecular Structure — PRECICE® HPRT Assay Kit

#K0709-01-2

#REF	SIZE	PRICE
#K0709-01-2	PRECICE® HPRT Assay Kit 10 ml, 24 analyses (8 samples in triplicate)	330.00 €	330.00 € Inquiry

Updated on July 2nd, 2025.

Kit is provided in stable lyophilized form and shipped without dry ice

Download HPRT assay Protocol (User manual)

Download Application Notes

Download Material Safety Data Sheet (MSDS)

🔎 Wide Detection Range

Detect HPRT activity from 6.75 to 340 nmol/hour/ml, capturing both complete and partial deficiencies.

🎯 Accurate

Low variability: 1.5% (within-run), 5% (between-day), and 6.5% (total imprecision).

⚡ Fast

Analyze up to 15 samples in triplicate in just 2 hours.

🧪 Convenient

Skip sample prep: use untreated cell lysates without inactivating 5'-nucleotidase.

✅ Validated

Results consistent with radiochemical protocols across erythrocytes, PBMCs, and cultured cells.

📦 Ready-to-Use

Supplied in a stable lyophilized form and shipped without dry ice—easy to store and prepare on demand.

HPRT Activity

Cell Type	PRECICE® HPRT Assay Kit (nmol/h/mg or per 10⁶ cells)	Published Data (nmol/h/mg or per 10⁶ cells)	Ref^*
RBC specimen 1 (n=4)	76.94 ± 2.5	80-120 (per mg Hgb)	4
RBC specimen 2 (n=12)	78.03 ± 5.52
RBC specimen 3 (n=4)	88.7 ± 3.41
PBMC specimen 1 (n=4)	159.91 ± 3.60 (per mg protein) 19.7 ± 0.6 (per 10⁶ PBMC)	343 ± 18 (per mg protein) 10.2-18.0 (per 10⁶ PBMC)	4
PBMC specimen 2 (n=4)	152.30 ± 4.94 (per mg protein) 21.3 ± 0.42 (per 10⁶ PBMC)	343 ± 18 (per mg protein) 10.2-18.0 (per 10⁶ PBMC)	5
Human Dermal Fibroblasts (Invitrogen)	70.91 ± 2.67	81-127 (per mg protein)	6
W20-17 cells (ATCC)	91.95 ± 4.49	81-127 (per mg protein)	6

Calibration curve of IMPDH-based PRECICE® HPRT Assay

The rate of the increase in absorbance at 340nm per hour as a function of the concentration of human recombinant HPRT enzyme (NovoCIB, ref. E-Nov-9). The changes in absorbance corresponding to 3 different control hemolysates diluted in complete reaction mixture to final hemoglobin concentration 1mg/ml (n=4) are shown by filled squares, filled triangles and filled circles. The insert shows a linear correlation observed in whole range of 21ng/ml up to 1.5µg/ml of recombinant HPRT; the units are the same.

🔬 Advantages of IMP-Dehydrogenase in the HPRT Assay

🎯 Targeted Specificity

IMPDH is highly selective for IMP, ensuring accurate downstream detection.

💊 Drug-Compatible

Allopurinol-insensitive—ideal for analyzing patient samples under treatment.

🔁 Reaction Directionality

Ensures irreversible forward flow from IMP to XMP, avoiding reverse HPRT activity.

🧪 Nucleotidase-Resistant

Excess IMPDH outcompetes endogenous 5'-nucleotidase, preserving assay accuracy.

📈 Real-Time Monitoring

Direct NADH readout at 340 nm enables continuous kinetic measurements.

💡 Research & Clinical Applications

🧬 Enzyme deficiency diagnosis — e.g., Lesch-Nyhan syndrome
🧬 HPRT mutation screening for functional studies and diagnostics
🧬 Drug screening targeting HPRTs of protozoan parasites (e.g., Plasmodium, Leishmania)
🧬 Toxicology assays using HPRT as a genotoxicity biomarker